Japan Business Tools MCP Server

Return the date that is N business days after (or before, if N is negative) the given date. The start date itself is not counted; e.g. 1 business day after a Friday is the next Monday unless it is a holiday. / n営業日後（nが負なら前）の日付。起算日は数えない。

Check whether a date is a business day in Japan, and if not, why (weekend, holiday name, bank closure, or a custom closed day). `reason` is Japanese text; `reason_code` is one of weekend, holiday, bank_closure, extra_holiday (null on business days). flags: `estimated`/`unverified` when the year's holidays are an estimate. / その日が営業日かどうかと、休みの理由（土日・祝日の名前・銀行の休業日・指定された休日）。reason_code は weekend・holiday・bank_closure・extra_holiday。

Look up a 13-digit Japanese corporate number (法人番号) in the National Tax Agency's monthly bulk data: name, furigana, English name, kind, registered address and postal code, assignment date, and closure (date, cause, successor) if the registry record was closed. The check digit (first digit) is verified first; a wrong check digit is reported as an input error. flags: `closed` (the registry record is closed — tell the user), `excluded_from_search`, `not_found`. This is not the invoice (qualified invoice issuer) registry. / 法人番号（13桁）から、名前・フリガナ・英語の名前・法人の種類・所在地・郵便番号・指定の日・閉鎖の日と事由・承継先を返す。国税庁の全件データ（月1回）。先頭の1桁（チェックデジット）を確かめ、合わなければ入力の誤りとして返す。インボイス（適格請求書発行事業者）の登録の確認ではない。

Look up the address (prefecture, city, town) for a 7-digit Japanese postal code, from Japan Post data. Accepts forms like 1000001, 100-0001 or 〒100-0001. One code can cover several towns; all are returned. `town_detail` holds the parenthesized part as written by Japan Post (e.g. chome ranges or building floors). If the code is a business-specific code (大口事業所個別番号) or a PO box code, the business is returned in `offices`. / 郵便番号から住所（都道府県・市区町村・町域）。日本郵便のデータ。1つの郵便番号に町域が複数あれば、すべて返す。事業所の個別郵便番号なら、事業所名と所在地を offices に返す。

If the date is a business day, return it as is; otherwise move to the next ("next") or previous ("previous") business day. Useful for payment due dates that fall on holidays. / 営業日ならその日、休みなら次（next）または前（previous）の営業日。支払日が休みのときなどに使う。

Find Japanese corporations whose name starts with the given text (prefix match), in the National Tax Agency's monthly bulk data. Legal-form words such as 株式会社 or 一般社団法人 are ignored at either end, and full/half-width and spaces are normalized. Matching in the middle of a name and furigana search are not supported. flags: `truncated`, `exact_match_only` (too many names start with the input; only exact matches returned), `not_found`. Returns up to 100 matches (`total`, `returned`, `truncated`) with corporate number, name, prefecture, city and `is_closed` (registry record closed); use lookup_corporate_number for details. Corporations marked as excluded from search on the NTA site are not included. / 名前の先頭から合う法人を探す（前方一致）。株式会社などの言葉は前後どちらにあっても無視し、全角・半角や空白の違いも吸収する。名前の途中からの検索とフリガナの検索はできない。最大100件。詳しい情報は lookup_corporate_number で。国税庁のサイトで検索対象除外の法人は入っていない。

Count business days from start to end, inclusive of both ends. Returns 0 if start is after end. The period can be up to 3,660 days (about 10 years). / start から end までの営業日の数（両端を含む）。start が end より後なら 0。期間は3,660日（約10年）まで。

Convert a Japanese era date to YYYY-MM-DD. Accepts 令和8年10月7日, 令和元年5月1日, R8.10.7, H31/4/30, Reiwa 8.10.7, kanji numerals (昭和六十四年一月七日), a trailing weekday such as （水） or 水曜日, and full-width characters. `input_era`/`input_era_year` echo the input; `actual` is the correct era for that date. If the date is outside the input era (e.g. 平成31年5月1日, written after the era changed), it is still converted by counting years, `within_era` is false and flags has `outside_era`. If a weekday was given and does not match, `weekday_matches` is false and flags has `weekday_mismatch`. / 和暦の日付を西暦にする。元号の範囲の外（平成31年5月1日など）も年を数えて変換し、within_era が false・flags に outside_era。曜日が合わなければ weekday_mismatch。

List all Japanese national holidays and substitute holidays for a year, based on the National Holidays Act and verified against the Cabinet Office CSV. Each holiday has `name` (descriptive) and `official_name` (as written by the Cabinet Office). / その年の国民の祝日・休日（振替休日・国民の休日を含む）の一覧。name は内容がわかる名前、official_name は内閣府の表記。

Convert a Gregorian date (YYYY-MM-DD) to the Japanese era calendar, e.g. 2026-10-07 → 令和8年10月7日 (wareki_short R8.10.07, zero-padded). Year 1 is written 元年. Supported from 1873-01-01 (the Gregorian calendar was adopted on 明治6年1月1日). Eras: 令和 (R) from 2019-05-01, 平成 (H) from 1989-01-08, 昭和 (S) from 1926-12-25, 大正 (T) from 1912-07-30, 明治 (M) from 1868-01-25. flags: `assumes_current_era` for dates after today (the era might change). / 西暦の日付を和暦にする。1年目は「元年」。明治6年（1873年）1月1日から。今日より後の日付には assumes_current_era。

Return the last business day of the given month. / その月の最終営業日。

Split a Japanese address into prefecture, city, town and the rest (block numbers, building), matching Japan Post's address data, and return candidate postal codes. Absorbs full/half-width, spacing, kanji vs. arabic numerals, ヶ/ケ and omitted county names; fills in the prefecture when the city is unique. Does NOT verify block/house numbers and has no coordinates. `level` tells how far the match went: 0 = nothing matched, 1 = prefecture only (see `city_candidates` if the city name is ambiguous), 2 = city matched but not the town (`postal_codes` are city-wide candidates), 3 = town matched. `address` and `municipality_code` are null below level 2. flags: `partial` (level below 3), `ambiguous` (several city or postal code candidates — ask the user or show all). / 住所を都道府県・市区町村・町域・残り（番地・建物名など）に分け、郵便番号の候補を返す（日本郵便のデータにあてはめる）。番地が実在するかの確認と緯度・経度はない。level：0＝わからない、1＝都道府県まで、2＝市区町村まで（町域はわからない）、3＝町域まで。

Find Japanese postal codes by prefecture, city and (optionally) part of the town name, from Japan Post data. The city must be the full municipality name (e.g. 札幌市中央区, 新宿区); the county name may be omitted. With `office_name`, searches business-specific codes (大口事業所個別番号) of businesses in that city by name instead. Returns up to 100 matches. / 都道府県・市区町村・町域（部分一致、任意）から郵便番号を探す。市区町村は正式な名前で（郡名は省いてよい）。office_name を指定すると、その市区町村の事業所の個別郵便番号を事業所名（部分一致）で探す。