Methodology and Sources
A linguistic reference is only as trustworthy as its sourcing. This page documents where every claim on NumbersInJapanese.com comes from, the romanisation and audio standards used, and the licences and attributions for the data on this site. Sources reviewed May 2026.
Primary sources
Every linguistic claim on NumbersInJapanese.com is reproducible from at least one of the sources below. URLs are live as of the “Last verified” date in the page header. Where sources conflict, both readings are noted and one is marked standard, formal, or rare.
| Source | Role | Refresh cadence |
|---|---|---|
| Agency for Cultural Affairs (Bunkacho) | Orthographic rulings, the Joyo Kanji list, government-level standardisation of written Japanese. The official body that revises the Joyo Kanji Cabinet Order (most recent 2010 revision, 2,136 kanji). | Annual; out-of-cycle on Cabinet Order revision |
| National Institute for Japanese Language and Linguistics (NINJAL / Kokken) | Corpus and lexicographic anchor. Maintains BCCWJ (Balanced Corpus of Contemporary Written Japanese) and the Shonagon retrieval interface. Backed by the Japanese Ministry of Education, Culture, Sports, Science and Technology. | Monthly; out-of-cycle on corpus update releases |
| Joyo Kanji Cabinet Order (2010 revision) | The official list of 2,136 standard kanji including all number kanji (一二三 etc.) and counter kanji (人本枚個匹頭羽時分回歳円). The authority on which kanji are taught in compulsory education. | On Cabinet Order revision (last 2010) |
| JLPT (Japanese-Language Proficiency Test) specification | N5 through N1 specification covering number kanji, counter words, and reading-variation conventions. Administered by the Japan Foundation and the Japan Educational Exchanges and Services. | On specification revision; annual study-guide releases |
| Japan Foundation (Kokusai Koryu Kikin) | JLPT administrator. Publisher of the Marugoto framework (CEFR-aligned A1 through B2 Japanese). Authoritative on what learners at each level are expected to know about numbers and counters. | On Marugoto / Marugoto Plus revision |
| NHK Broadcasting Pronunciation Dictionary (Hoso Bunka Kenkyusho) | The standard reference for Japanese pitch accent and pronunciation in broadcast media. Sets the modified Hepburn romanisation conventions for macrons, apostrophes, and the n-before-bilabial rule (sanpo, not sampo). | Annual; out-of-cycle on edition release |
| Daijisen and Daijirin (via Goo dictionary) | Native-Japanese dictionary cross-reference for cardinal and ordinal forms, native (Yamato) versus Sino readings, and the historical etymology of irregular forms (hitori, futari, hatachi, tsuitachi). | Annual; on edition release |
| Kanjipedia | Stroke order, on-yomi / kun-yomi readings, daiji formal-kanji forms (壱弐参拾佰仟萬). The kanji-handwriting authority operated by the Japan Kanji Aptitude Testing Foundation. | Monthly cross-check |
| Tofugu | Secondary cross-reference for counter pedagogy: per-counter articles on mai, hon, ko, tsu, hiki, with the cleanest English-language sound-change tables. Used to verify rendaku and gemination patterns. | Monthly cross-check |
| WaniKani | Kanji learning cross-reference for stroke order, mnemonic context, and intermediate-level kanji teaching. Used to cross-verify stroke counts and reading variants. | Monthly cross-check |
| Imabi grammar guide | Cross-reference for advanced grammar around number-counter morphology and the historical development of the man-oku-cho system. Used where Daijisen / Daijirin entries are terse. | Monthly cross-check |
| Genki I and Genki II (Banno et al., 3rd edition 2020) | The Japan Times textbook benchmark for A1 to A2 Japanese including the 12 essential counter words and the 1-to-100 + man / oku / cho system. Cross-referenced for what counts as core curriculum. | On edition release; current 3rd edition is the baseline |
| Marugoto framework (Japan Foundation) | CEFR-aligned A1 to B2 Japanese curriculum with explicit can-do statements at each level. Used to position the per-page educationalLevel attribute on LearningResource schema. | On framework revision |
In scope
- Sino-Japanese number morphology 1 to 99 and the 11-99 build rule (ju-ichi, ni-ju, ni-ju-go, kyu-ju-kyu).
- Native (Yamato) numbers 1 to 10 (hitotsu, futatsu, mittsu) and the surviving applications (tsu counter, day-of-month names tsuitachi / futsuka / yokka, hitori / futari).
- Big-number 4-digit grouping: man (10^4), oku (10^8), cho (10^12), kei (10^16); and the boundary arithmetic.
- The counter-word system (josuushi, 助数詞): the 12 essential counters with sound-changes, plus the Yamato versus Sino classification.
- Date / time / age / phone / price / address formatting in Japanese, including the Reiwa imperial-year calendar arithmetic (Reiwa 8 = 2026).
- Reading variations at 4 / 7 / 9 (yon vs shi, nana vs shichi, kyu vs ku) and the cultural-convention background.
- Writing systems: Arabic numerals, kanji 一二三, hiragana, and the formal daiji set 壱弐参拾佰仟萬 used on cheques and contracts.
Out of scope
- Translation services. Use a professional translator or DeepL / Google Translate for translation, not a number reference.
- Full Japanese grammar instruction. Pair this site with Genki, Tobira, Marugoto, Imabi, or a tutor for grammar.
- Idiomatic numeric expressions (sansan-go-go for “in twos and threes”, kuugen for “empty words”) beyond the core mention on the relevant page.
- Regional dialect numerals beyond standard Japanese (hyojun-go). Kansai / Tohoku dialect numerals are documented in NINJAL corpus material but out of scope for this reference.
- Individual learner placement testing. The JLPT, Marugoto Plus, and J-CAT are the placement-test authorities.
- Content beyond numerical morphology and the counter system. Kanji compounds unrelated to numbers, general vocabulary, and conversational Japanese are out of scope.
Verification framework
The site uses a five-layer verification pattern:
Refresh cadence
Sources are reviewed monthly during the first business week. The single LAST_VERIFIED_DATE constant in src/lib/schema.ts drives every freshness indicator across the site: page-hero stamp, footer copy, Article schema dateModified, LearningResource dateModified. Roll the constant forward once and every freshness signal updates.
Out-of-cycle refresh triggers:
- Bunkacho orthographic ruling or Joyo Kanji Cabinet Order revision.
- NHK Broadcasting Pronunciation Dictionary edition release (annual reference revision).
- JLPT specification revision or Japan Foundation Marugoto framework update.
- Daijisen / Daijirin / Kojien new edition.
- Flagged correction received via the corrections email.
Romanisation standard
Modified Hepburn, per the NHK Broadcasting Pronunciation Dictionary convention. Macrons used for long vowels (ju, kyu, cho, to). Long vowels are not doubled (ju not juu). Apostrophes disambiguate where needed (kin'youbi, not kinyoubi). The ん (n) sound is written n (not m) before b, m, p (sanpo, not sampo) per the NHK rule.
Audio policy
Audio buttons use the Web Speech API with the ja-JP voice. Quality varies by browser and device. Where the API is unavailable, the page indicates “audio unsupported”. This site does not voice-clone, scrape Forvo, or synthesise audio server-side. A future commission of native-speaker MP3s will supplement the most-used entries; until then, treat the Web Speech audio as approximate and cross-check pronunciation against the NHK Pronunciation Dictionary or a native speaker.
Image policy
No DALL-E or generative imagery for kanji. Generative AI is unreliable with kanji shapes. Every kanji on this site is rendered as Unicode text in Noto Sans JP and Noto Serif JP, two open-source fonts maintained by Google. Stroke counts reference KanjiVG (CC-BY-SA 3.0); future stroke-order animations will use KanjiVG SVG data with full attribution.
KanjiVG attribution
Stroke-count data and any future stroke-order diagrams derive from KanjiVG, a project by Ulrich Apel, released under the Creative Commons Attribution-Share Alike 3.0 licence (CC-BY-SA 3.0). We thank the contributors and credit the project here, on the relevant content pages, and in the project log.
Limitations
- Regional dialect variation: Kansai, Tohoku, Kyushu, and Okinawa dialects have number-related variants that this site does not cover. The standard (hyojun-go) is the scope.
- Audio variance by browser: Web Speech API ja-JP voice quality differs between Chrome / Edge / Safari / Firefox and across operating systems. Some browsers fall back to a synthetic voice that may mispronounce edge cases.
- Kanji rendering by font availability: in environments without Noto Sans JP / Noto Serif JP installed, kanji may render in a system fallback font with different visual proportions.
- Historical drift in literary texts: Heian-period and pre-Meiji texts use number conventions (e.g. ozaki for 100, momo for 100) that have fallen out of modern usage. This site documents modern standard Japanese.
- IPA broad versus narrow transcription: Japanese pitch accent is not represented on this site beyond what the NHK convention captures in romanisation. Narrow phonetic transcription would require IPA tone marks not in the standard reference convention.
Disclaimer
NumbersInJapanese.com is an independent language-learning reference. It is not affiliated with Bunkacho, NINJAL, the Japan Foundation, NHK, the JLPT administering body, Tofugu, WaniKani, Busuu, Rosetta Stone, Genki / Tobira publishers (The Japan Times), Imabi, Kanjipedia, or any Japanese-language educational publisher. Romanisation follows modified Hepburn per the NHK convention. Audio uses the Web Speech API ja-JP voice.
Corrections process
Spotted an error? Email hello@digitalsignet.com. Five-business-day SLA on correction acknowledgements. Three-bullet email format:
- Page URL where the error appears.
- Specific claim that is wrong, with the corrected reading or rule.
- Primary source supporting the correction (Bunkacho ruling, NINJAL corpus entry, NHK Pronunciation Dictionary entry, Joyo Kanji list, Daijisen / Daijirin entry, Kanjipedia entry).
For tutoring or accredited Japanese-language tuition, please contact the Japan Foundation, your local JLPT administering body, or a certified instructor. NumbersInJapanese.com does not offer tutoring services.