All about Japanese personal inkan/hanko/chops/seals

"signing" a payment slip at a bank

In Japan (and other Asian countries), it is traditional practice to use an 印鑑 {inkan} (aka 印章 {inshō}) — colloquially called a 判子 {hanko} in Japanese or "chop" in British English — instead of a signature for acknowledging / signing / accepting documents.

Pedantically speaking, a 判子hanko is the actual stamping object, and an 印鑑inkan is the ink impression that is made, but many native Japanese use the two words interchangeably.

In the 21st century, Japanese recommend having three types of seals:

1. one for casual informal acceptance: 認印 {mitomein}
2. one for your bank accounts: 銀行印 {ginkō-in}
3. the "real" registered one: (実印 {jitsuin})

While it's perfectly possible to use just one seal for all of these functions, most people use at least two or three for the same reason that people should use different passwords for different services on the internet: in the case of a compromised seal, that seal cannot be used for other functions.

Similar to how just having a password alone on to log into internet services is not considered secure enough these days (other companies, including Google, optionally provide 2-factor authentication to supplement password systems), most of the places where you will need to use a seal these days (for bank transactions and major contracts) ensure that the seal is in the possession of the rightful owner by using a second authentication factor: a proof of registration certificate for contracts — which can only be obtained with a special card & passcode, or physical identification or a bank passbook.

The "real" registered seal: 実印 {jitsuin}

The real seal (実印 {jitsuin}) is registered at the 市役所／区役所 {shiyakusho / kuyakusho} (city hall / ward office) etc. and is only used for serious contractual matters things such as the contract for a mortgage loan for purchasing a house or a business loan. This is often the largest (about the diameter of your thumb: 15mm to 18mm) seal.

For major transactions (for example, a mortgage loan) that require the use of your 実印 {jitsuin}, you'll need to present a copy of your proof of registration, which proves that you are the rightful owner of that particular seal.

Making and registering your seal at your local municipal office

There are shops all around Japan (brick & mortar and online) that will make seals for you in the regulation size. For it to be a seal that you use as a 実印jitsuin however, the name on it will have to be the same as your legal name registered at the municipal office. If you are naturalized, this will be your 漢字・仮名kanji · kana name. If you are non-Japanese, this will be either your alphabetic passport name or it will be your registered Japanese alias (通称tsūshō). Because there are only so many characters that can fit in a regulation sized seal and foreign names in alphabet can be long, some of the names can be abbreviated. Common permissible Japanese name, foreign name, and alias name combinations allowed on 実印jitsuin depend on the locale. A typical locale's rules are as follows:

Name: Smith, John　Alias: スミス ジョン {SUMISU Jon}

• The full alphabetic passport name — family name followed by given name(s) — is okay
• An initialized (頭文字 {kashiramoji}) name and a full name combination is okay
• A registered Japanese alias (通称 {tsūshō}) is okay

Name: Smith, John　Alias: スミス ジョン {SUMISU Jon}

• 通称 {tsūshō} (aliases) which have not been registered are not okay
• A mix of the alphabetic passport name (full or abbreviated) and the 通称 {tsūshō} (alias) is not okay
• Unregistered 当て字 {ateji} (sinograms corresponding to either an alias or a real name) are not okay

Name: 劉 志映 {LIÚ Zhìyìng}　Alias: 葛飾 太郎 {KATSUSHIKA Tarō}

• simplified Chinese (中国簡体字 {Chūgoku kantaiji}) equivalants of the same original characters are okay — just having the family name is okay too.
• Modern / "new" Japanese sinograms (新字体 {shinjitai}) versions of a legal / registered 漢字 {kanji} (CJKV sinogram) names are okay
• Japanese registered aliases (通称 {tsūshō}) are okay

Name: 劉 志映 {LIÚ Zhìyìng}　Alias: 葛飾 太郎 {KATSUSHIKA Tarō}

• mixing a registered 漢字 {kanji} (sinogram) family name (姓 {sei}) and a registered Japanese alias (通称 {tsūshō}) given name (名 {na}) is not okay
• mixing a Japanese alias (通称 {tsūshō}) family name (姓 {sei}) with a 漢字 {kanji} (sinogram) given name (名 {na}) is not okay
• Having only parts / one or a few characters of the registered 漢字 {kanji} (sinogram) — real name or alias — is not okay.

CAVEAT: Depending on the locale, these sample rules above may be stricter or looser. For example, some locales do not allow 頭文字 {kashiramoji} (initials) for alphabetic names. Check with your local municipal office to see what's permitted. It is possible that a seal that is valid to be registered in one locale is not valid in another locale in Japan. Example: alphabetic initials (頭文字 {kashiramoji}) are not permitted to be registered in 東京都渋谷区 {Tōkyō-to Shibuya-ku} (Shibuya, Tokyo).

The reason why one can get away with using just one name (family or given) or a name plus an initial (頭文字 {kashiramoji}), rather than the full name on a seal, is because:

• in the case of a real registered seal (実印 {jitsuin}), the certificate that you will submit with the document having your seal impression will have your full legal name on it (as well as a facsimile of your seal imprint)
• in the case of a bank seal (銀行印 {ginkōin}), your bank with have a copy of the impression of your seal, which will be linked to your account name

You can only register one seal per person. Registering usually costs a small fee around ¥100.

Cost of a real seal and accessories

A rather ornate seal safety case with ink pad

Having a real personal seal made for Japan depends on the material used (it can range from basic wood to real elephant ivory), the size, and number of characters. The prices can range from ¥100 for an "off-the-rack" seal (that are not permitted to be used for banks and registered seals) to ¥10,000 and beyond, but on average you should plan on spending ¥3,000 to ¥5,000 for a custom one that will last you a lifetime (providing you don't change names). Because the seal is hand made and unique, it will usually take a week or longer for it to be made.

You will want to get a hard case for your seal, as while the seal itself, even those made in wood, are durable, the engraved character strokes are thin and can crack and break easily.

Most plastic cases can be had for a few thousand 円 {en} (Japanese yen), and include a small changeable 印肉 {inniku} (ink pad) built into them, although most banks will provide their own ink pads when using a seal becomes necessary. The mass produced cases will handle seals with a diameter of up to 18mm and a length of up to 6cm and resemble a thick lipstick case. It will keep the seal clean and allow you to slip it into a pants pocket. In addition to hard cases, there are also soft pouches for seals.

Some of the cases, like smartphone cases, can be quite personalized and stylized and fancy.

Getting a 印鑑登録証明書 {inkan tōroku shōmeisho} (proof of registered seal)

There are two ways to get a certified copy of your registration:

1. via a self service machine (which usually costs around ¥200). This is the most convenient method
2. via a human public servant working at the office where your registered your seal (which usually costs around ¥300)

sample Yokohama City seal proof retrieval card

If you use the automated self-service machine, you will need a four (4) digit 暗証番号 {anshōbangō} (secret code) to retrieve a copy of your "proof of registered seal" as well as your issued magnetic stripe card that you received when you registered your seal.

Some locales also let you use your 住基カード {jūki kādo} (Multipurpose Registered Resident Card — aka 住民基本台帳カード {jūmin kihon daichō kādo}) to issue copies of your 印鑑登録証明書 {inkan tōroku shōmei-sho} (proof of registered seal).

Self-Service Seal Proof Issuing Machine

This computer laser-printed (on photo-copy duplication and forgery resistant paper) 印鑑登録証明書 {inkan tōroku shōmei-sho} (proof of registered seal) you receive will have the following information on it:

• Your legal alphabet passport name, or 漢字／仮名kanji / kana (Japanese sinograms or syllabet) name). If you are a foreign national and you have a Japanese registered alias (通称tsūshō), this will also be listed after the passport name, in parenthesis.
  
  The names will be the exactly the same as what is on a Japanese national's 戸籍 {koseki} (family register) or a non-Japanese Resident Card (在留カード {zairyū kādo}).
• Your registered residential home address (住所 {jūsho})
• Your birthdate (生年月日 {seinengappi}). The year of birth will be in 和暦 {wareki} (Japanese emperor era years)
• Your sex (性別 {seibetsu}). Some locales do not list this in consideration for those with gender identity issues
• date of issue (発行日 {hakkōbi}). The printed proof is only valid for three (3) months from the date of issue.
• a monochrome clean printed impression of your 実印 {jitsuin} (real seal) at the exact 1:1 scale

The bank-use seal: 銀行印 {ginkō-in}

Nowadays they recommend using a different seal from your real registered one just for your bank accounts. Thus, most people will have another custom seal made just for this security. It's the one most Japanese use second most often after their personal unregistered seal. It will be medium sized (about the size of your index finger: 13.5mm to 18mm). There are size and shape restrictions in that the impressed image must fit within the dotted red circle on bank forms.

The inside cover of a bank statement book
Statement books in Japan can also serve as bank IDs

Not long ago, a copy of the impression was in your bank statement book (銀行通帳 {ginkō tsūchō}). For security reasons, most banks no longer do this. An impression of your bank seal is always kept at the bank in your file, so the bank can compare this impression with the one you make when you're doing a financial transaction.

To use an ATM in Japan, all you need is your bank card and knowledge of your PIN; you don't need your seal.

To perform a more complicated transaction with a teller, you will need either:

• your bank card, knowledge of the PIN, and possibly an additional official/photo ID (身分証明書 {mibun shōmei-sho}) depending on the bank policies
• Your bank statement book (銀行通帳 {ginkō tsūchō}), your 銀行印 {ginkō-in} (bank seal), and possibly an additional personal ID (身分証明書 {mibun shōmei-sho}) depending on the bank policies

For many Japanese banks, online banking often requires anywhere from two to three factors of identification beyond a simple PIN, depending on the transaction. For example, simply checking one's balance requires the bank account number and the PIN.

Because most banks require physical identification in addition to other identifying documents, some banks in Japan in the 21st century will allow you to use a western-style written signature instead of a seal. However, the use of seals is still common for Japanese banking. What has changed from the 20th century is that banks recommend you use a seal separate from your real registered one (実印 {jitsuin}) for security reasons.

Many (but not all) banks will allow their seals to be almost anything in terms of the design; the impression does not have to be directly connected to your legal names or aliases. In some cases, the impression does not even have to be characters.

The unofficial unregistered personal seal: 認印 {mitomein}

Hundreds of common last names mass
produced on cheap ¥100 seals

Finally, for "signing" or acknowledging things like the formal shared group notices (回覧板 {kairanban}) that go around the neighborhood, apartment building or office, etc. — or accepting packages at the door — you'll want a casual, non-secure seal. Some of these have built in self-inking auto-mechanisms or are ゴム印 {gomu in} (rubber or partially rubber stamps). For example, my personal seal, because my family name 井上 {INOUE} is very common, was bought off-the-shelf at a "¥100 Store" — similar to a dollar store in other countries. I can do this because my Japanese family name is one of the top twenty most common family names in Japan!

There is a variant of the this seal called the 訂正印 {teiseiin} (correction stamp). This stamp is usually even smaller stamp than the normal personal seal, and is often oval shaped. Its purpose is to affix the seal next to crossed out (like this: Suzuko Suzuki) mistakes in a document, indicating who it was that made the correction in the document. Like the personal seal, they can often be bought mass-produced off-the-rack for common Japanese family names.

These mass-produced, identical, non-individual seals are not valid for either the banks or formal contracts or loans.

delivery to the person rather
than leaving parcels at the door
is the norm in Japan

Whenever a delivery person comes to your home, they'll often assume you don't have your personal seal handy or near your person (or they may be assuming you don't have one at all if you appear to be a foreign resident) — or you may not have an ink pad (印肉 {inniku}) nearby (this is why keeping a self-inking seal near the doorway area is not uncommon in Japan) so they'll ask for your サイン {sain} (signature) instead, pointing to an "acknowledgement of receipt of parcel" area on a form that was meant for a seal (a small red circle about one centimeter in diameter). The 外来語 {gairaigo} (foreign loan word) 『サイン』 {"sain"} does not have the exact same nuance as "signature" in English in that most Japanese expect the letters of a サイン {sain} to be legible: 活字 {katsuji} (block print style script).

Because the circle is so small, there will only be room to write your initials in it. And that's fine for most delivery people.

Some very small personal unregistered seals are in the shape of ovals rather than circles. Because the seals are not registered anywhere, there are no rules as to what the seal impression must be. Whether the seal impression and shape is acceptable or not depends on the situation and use case.

Some delivery services (especially if they're international) have switched to digital tablets, which require a signature on a touch screen using a finger or a stylus. These services have abandoned using the Japanese personal seal system.

These days, in the 21st century, most places that accept these "disposable" 認印 {mitomein} will also accept a signature/scribble in lieu of a stamp.

An even smaller seal: 訂正印 {teisei-in} (Corrections Seal)

The 『も』 {"mo"} has been changed to a 『ま』 {"ma"}.

A variation of the 認印 {mitomein} is the 訂正印 {teisei-in} (corrections seal), which is identical to a 認印 {mitomein} in purpose except that it's designed to mark corrections. For example, if you make a typo on a form, the protocol is usually to cross out the incorrect letters, numbers, or words with a strikeout using double lines (二重線 {nijūsen}), write the correction as close as possible, then affix the corrector's 訂正印 {teisei-in} as close as possible to the incorrect and corrected characters.

You can usually use a non-dedicated seal to denote corrections as well — the 訂正印 {teisei-in} may simply be more convenient because it's the smallest and often the space and acknowledge corrections on a form is small.

The novelty seal

Novelty seals intended for wedding invitations

As seals have been a part of Asian culture for many years, there are tons of novelty and fun and toy seals for sale everywhere, both for adults and kids.

Some of them actually incorporate one's name and are custom made. They may have novelty images as part of the design.

As long as these designs meet the criteria (not rubber, custom made and unique, proper size dimensions, proper name, etc), it's possible to use one of these as a registered seal or bank seal.

Most of the time, however, these seals are used simply for fun or novelty, such as stamping the end of a personal handwritten note or letter.

The tourist / souvenir / gift Chinese chop

Pretty & elegant, but not practical for Japan

There are many online ads and many tourist shops that sell so called "Chinese chops". They are often quite ornate and fancy, and the shops will offer to "translate" your name into "Chinese characters" for you.

Remember that the method and choice of characters used for translating a foreign name into 漢字 {kanji} (CJKV sinograms) is different for Chinese and Japanese. Thus, the 当て字 {ateji} chosen by a Chinese engraver will not be easily readable or understood by a Japanese person.

Also, the sinograms used by various countries have changed over history. Chinese use either 簡体字 {kantaiji} — simplified Chinese sinograms [PRC, Singapore]) or 繁体字 {hantaiji} (traditional Chinese sinograms [ROC/台湾 {Taiwan}, 香港 {Hon Kon} (Hong Kong)]. These are not always the same as the 新字体 {shinjitai} (new [post WW2] Japanese sinograms) or the 旧字体 {kyūtaiji} (old fashioned Japanese sinograms).

While there's often nothing wrong about the quality or value of these seals, you should avoid getting one because the size and shape of the seal will often be inappropriate for practical real-life use in Japan.

A seal used in Japan is relatively small (maximum of 18mm diameter, which 12mm to 15mm being more typical), made of durable and lightweight material, and portable enough to put in your pocket with a carrying case.

Also, there are restrictions on the design you can use if it's being used for purposes other than a 認印 {mitomein} (personal unregistered seal).

Security of the seal

The personal cursive signature is a dying art

The security of the seal is similar to a written cursive signature in that in theory, it's hard for an amateur to perfectly copy the after-the-fact impression made by one, and the original, one-of-a-kind design.

Thus, like a signature, people are protective about the impression made and where it is done because they do not want to make the image it makes publicly know — lest it be easier to copy.

Like a cursive signature, one of the problems is that an amateur can sometimes do a good enough job mimicking the impression that it takes an expert who is trained in spotting counterfeits to be able to tell the difference between a false copy and the real impression.

Like signatures and their susceptibility to being copied "just good enough" to fool an untrained eye (in addition to the seals vulnerability to being stolen), the 21st century has supplanted or boosted the security of the seal by requiring that serious transactions with a seal be accompanied with identification and/or a certificate of registration.

How to make an impression

One good and six bad examples of 小石 {KOISHI}

Affixing your seal to a document is somewhat like using chopsticks (箸 {hashi}): anybody can do it, but it does require practice in order to make a good, acceptable, imprint. It is harder to make an imprint with a real seal than a typical stamp/seal because a typical stamp/seal is rubber and soft; if you come down at an angle, enough pressure will usually ensure a good impression. Also, the rubber prevents your seal from slipping or rotating slightly during imprint, leaving a smudged or overprinted impression.

When using an ink pad (印肉 {inniku} — also called a 肉池 {nikuchi} or 印池 {inchi}), you should make sure the pad is not dry and figure out how many times and how hard to dip the seal into the pad. Too little, and the impression may be too light or faint. Too much, and the impression may smudge. It is a good idea to use a tissue and wipe the seal area clean both before dipping and after making the impression. Only use proper ink pads that use have the proper color: 朱色 {shuiro} (vermillion; scarlet). The pad should look like an orange-ish to red. An ink pad that uses this proper color is called a 朱肉 {shuniku}.

When making the impression, make sure you know which side is up. Some stamps have a notch or mark on their handle indicating which side is up. Others don't, so you'll have to look at the inverted image at the end of the seal to figure it out each time.

Fortunately, most people that deal with stamps as part of their job will offer to affix your seal (with you directly witnessing it) for you; most bank tellers will have their own pad and will properly clean your seal before and afterwards.

Seals are used in the same way that signatures (and signing your initials) are used in the European documents:

• they are placed besides one's printed name
• they are played over corrections, deletions, corrections, and mistakes
• they are placed in their own designated area (instead of a dotted line, a dotted circle)
• they are placed so that the impression overlaps two or more pages (to prove that which pages go together and to prove that no pages are missing)

There are rules as to whether the impression should go over the text or besides the text, as well as how near the impression should be to the text. Some general guidelines:

• If it is important that the original text on the document be easily readable, then do not stamp over the text (example, your printed name)
• If it is important that the seal be verifiable and have no background distractions, then do not stamp over text and make sure that the impression is made within the designated area (usually a box or circle)
• If the seal is accompanying your name, it should be near the name — about a half to a full character space from the end of it — below if 縦書き {tategaki} (vertical writing) or to the right if 横書き {yokogaki} (horizontal writing)
• If it is to acknowledge a handwritten correction of mistake it should be overlapping the mistake or beside the change.
• If the seal impression itself is a mistake the impression should be crossed out, using an ink pen — with two horizontal lines.

An impression made by a seal is not considered to be valid if it is a photocopy, a FAX, or any other sort of digital or analog copy.

Seal materials

Not all ivory is illegal

Some people believe that all seals are made of exotic materials: expensive marble and exotic (and sometimes even banned) ivory or ebony.

The vast majority of personal seals these days are wood or plastic based. They may also be made out of synthetics designed to resemble ivory or ebony. It is true that you can still get seals made out of exotic materials — even titanium — though they will be extremely expensive.

Not all ivory is taken from endangered or threatened animals. There are trade regulations governing the controlled and sustainable use of ivory that all merchants in Japan are supposed to abide by. If you do decide to have a seal made from real elephant ivory, make sure to look for the 経済産業省・環境省 {keizai sangyō shō · kankyōshō} (Ministry of Economy, Trade and Industry [METI] & Ministry of the Environment [MOE]) marks on the product to insure it has been inspected and comes from stockpiles or sustainable sources.

Almost every handmade seal is unique

It's statistically unlikely that two are alike

A handmade seal has the characters engraved by a craftsman using tools (although some parts of the engraving process are automated and use machine based tools these days). This in theory makes it highly unlikely that two seals will be perfectly alike, even if they're the same name and engraved by the same person.

Although to the untrained eye, two seals may appear to be identical, they shouldn't be. Even if the difference is a spacing or a length of a stroke that differs by a millimeter or less.

This is no different if the design or number of characters is simple or complex.

This is why when you lose your seal, and you have a new one made, you must re-register the new seal and report the old one as lost, destroyed, or stolen. The seal may look almost identical to the old one and have the same name, style, spacing and shape, but there will by minute differences that only a trained eye (perhaps assisted with a magnifying glass) will be able to spot.

Choice and number and style of characters

Pragmatically speaking, you can have 当て字 {ateji} (individual sinograms phonetically corresponding to a foreign word), but the physics of making the small seal size means you'll probably be limited to four characters tops. maybe five for a big corporate seal.

The family name ITŌ in various font/styles

From left to right, the font/glyph styles go from most old fashioned / traditional to most contemporary. The 篆書体 {tenshotai} (seal script) style, which is the most old fashioned and traditional style — shown on the far left of the 伊藤 {ITŌ} example above, may not be readable to all, depending on the complexity of the character, as it is more of a calligraphic seal style than actual script using in living language.

None of these are required to be the same style or name, btw. As a non-Japanese, you could have a 片仮名 認印 {katakana mitomein} (syllabet personal seal) and an 当て字 銀行印 {ateji ginkōin} (sinogram bank seal) one, for example.

Size of the seal

The Emperor's formal seal is huge

Almost all seals for people in Japan are circular and 60mm in length with a maximum diameter of less than 2cm (more typically 1.5cm or less). Notable exceptions are the seals for public officials and heads of state: the Prime Minister of Japan and the Emperor's seal are two famous examples, as these seals are often found on public documents (such as the Constitution of Japan) and laws.

The registered seals for corporations tend to be bigger and often square compared to seals for individuals. The bigger and older and more famous the company, the larger the seal.

Corporate seals will also tend to be more complex with the layout of the characters, and may have characters going around the perimeter, designs and logos, etc.

Men's vs. Women's Sizes

Much like there is feminine fashion and masculine fashion, there are sizes of seals that are considered feminine and sizes that are considered to be more masculine. Much like the fashion world, these rules are not set in stone. Just as a women can wear jeans these days, a woman can also have and use a seal that would be considered to be a more "masculine" size — and vice versa.

Still, traditionally Japanese women have preferred seals which are smaller in diameter than men's.

personal (non-business) seals should be circular

Recommended diameters for Japanese seals
Size (mm ⌀)	10.5	12.0	13.5	15.0	16.5	18.0	19.5
masculinity/femininity		♀	♀|♂	♀|♂	♂	♂
casual use: Receiving packages, acknowledging memos	○	◎	○
bank account use		○	◎	◎
formal use: contracts, loans & mortgages			○	◎	◎	○

As you can see from the above chart, the sizes between 13.5mm and 15mm are not only considered unisex, but they're also the sizes that are accepted for all uses, from registered to not registered, as well as for bank use.

In addition to the diameter size, the other cluses that a seal will be feminine or masculine will be the name itself (obviously), the choice of font and characters, and the colors of the accessories used to hold the seal.

Maximum Number of Characters

Much like how there is no real limit on the number of characters you can have in your Japanese name, their is no legal or stipulated limit to the number of characters you can have on seals. It depends on the size of the area to engrave, the skill of the engraver, and the materials used.

However, also like a real Japanese name, there are very definite pragmatic and physical barriers and limits to the number of characters you can before it becomes unwieldy. For all practical purposes, this chart shows the limits for most typical seals with typical fonts/glyphs:

The letter "m" and other wide characters may count as two units

φ幅 {fai haba} (diameter width)	maximum possible characters
	漢字・かな {kanji · kana} 全角文字 {zenkaku moji} (full sinogram width)	アルファベット {arufabetto} (alphabet) 半角文字 {hankaku moji} (half sinogram width)
12.0mm	1 line: 2 to 3 characters	1 line: 6 to 7 characters
13.5mm	1 line: 3 characters	1 line: 7 to 8 characters
15.0mm	2 lines: 3 to 4 characters each for: family & given names	2 lines: 6 to 7 characters per line OR 8 to 9 characters in one line

Official registered seals for foreign names, due to their inherit length, depending on the locale, may be given a little more latitude than Japanese names in that one of the names may be abbreviated to a 頭文字 {kashira moji} (initial[s]). For example, the name "JOHN SMITH" may be engraved as "SMITH J." or "S. JOHN" in some locales. In other locales, just one name (usually the family name) may be acceptable.

Are old fashioned seals even necessary in Japan anymore?

You don't see this in stores, but you do see some
Japanese home delivery companies use these.

Every once and a while I see a response to a question about seals in Japan from somebody new and the other people advise "don't bother, you can sign for things just fine."

And the person giving the advice may be 100% correct from their personal experience: depending on the type of bank account you have, and the type of home you live in, and the type of business you do, you might have a lifestyle in Japan that very rarely to never uses a seal for any type of business.

A few decades ago, if you had asked a delivery person if you could "sign" for something instead of use a seal, they probably would have been uncomfortable with you doing it.

And with modern technology making more digital forms of acknowledgement more and more common — not just in Japan but the rest of the world — the act of using a seal, or a signature, may go the way of cursive handwriting thanks to word processing.

Those without Japanese nationality can use their signature in lieu

Those who only have foreign nationality doing business or living in Japan (外国籍 {gaikokuseki}) are allowed by law to substitute using their signature in all places where impressing a seal is required. In the case where a certificate proving registration of a seal is required, one obtains a サイン証明書 {sain shōmeisho} aka 著名証明書 {chomei shōmeisho} (proof of signature document) with a company or one's vital details from their embassy or consulate — this is recognized as a substitute for the 印鑑登録証明書 {inkan tōroku shōmeisho} (proof of seal registration).

Do you need a new or different seal after naturalizing?

If your name changes, either due to marriage, personal reasons, or naturalization, you'll probably need a new seal if it had your old name. You will not need to change existing contracts that used your old seal, however, because those old contracts have a proof of registration that links the imprint of your old stamp to your legal name at the time. You still may have to change the legal name on existing contracts, however.

Also, if you never used a seal before as a foreigner in Japan, once you naturalize you may need to have one. While there is no legal obligation to possess a registered and/or bank seal, only those who are not Japanese nationals are legally permitted to substitute their signature for a seal whenever one is required.

If you change from a カタカナ {katakana} (Japanese syllabet [for foreign names]) name or an 当て字 {ateji} (Japanese sinograms [for foreign names]) alias, you will need to register a new seal for both your official seal and your bank seal.

It's very possible for a non-Japanese to have started with a 漢字 当て字 {kanji ateji} (foreign name mapped to Japanese sinograms) seal — due to their 通称tsūshō (registered alias) — when they first came to Japan and then end up changing to a 仮名 {kana} (syllabet) name after they become Japanese.

Fortunately, registering a new seal is not as hard as changing your name: the procedure is pretty much identical to the procedure for registering a new seal when your old seal is lost, destroyed, or stolen.

As for your personal seal, it is not necessary to inform anybody. Very few people will ever see what's on your 印鑑 {inkan} (seal/"chop") with the exception of your 認印 {mitomein} (personal seal), so you can change it and nobody will ever know.

Making a digital/web seal

A non-Japanese name seal (φ13.5mm)

You may encounter digital images of seals on the internet or inside Microsoft Word or Excel documents. These are called 電子印鑑 {denshi inkan} (electronic seals; "e-stamps/seals/chops") or ウェブ認印 {webu mitomein} (personal web seals). They are used in ways similar to how 認印 {mitomein} are used: for unofficial, non-legal, acknowledgement of receipt or understanding. They are also used for novelty.

There is a lot of software out there that will help you make your own seal. Much of this software is free (the monetization hook is the company that makes & distributes the software hopes you will use the images as a model/template for ordering real seals for money).

In fact, there is an awful lot of software out there to mimic the old fashioned process of affixing a seal; this is probably because software vendors are trying to take advantage of Japanese firms that are trying to convert to a completely paperless office without needing to convert the actual process (and the people in charge of those processes) Some go so far as to office hardware peripherals that mimic the size/shape of a physical seal so that you can virtually "stamp" the document by affixing the faux seal to a display!

For the same reasons as why digitizing your real signature and using it on the net is a bad idea, it's probably a bad idea to use the image produced by this software both publicly and as either your bank seal or your real registered seal.

For those that don't want to download or install software, there are many services that will generate an image for you on the web. Most of this software is designed for Chinese — some Japanese characters may be unavailable and the glyphs may be in a non-Japanese style — but there are a few web services that will generate Japanese.