Japan Business Tools
Check Japanese holidays, business days, and calculate deadlines accounting for weekends and closures.
Provides Japanese national holidays, business day calculations, and date adjustments for Japan. Helps determine if a date is a business day, count working days between dates, and shift deadlines to the next or previous business day.
Try asking Muse: "Tell me the last business day of this month in Japan so I know when to schedule a payment."
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Source: Found in the official MCP Registry (jp.ossalt/jp-biz-tools) · First listed October 28, 2026
Last 24 hours
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Is it safe to connect?
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How to add it to Muse
Not in Muse's Connectors list yet, but Muse can still use it. Copy the request below and paste it into Muse. Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
https://biz.ossalt.jp/mcpNot in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
Also use it in ChatGPT or Claude
Japan Business Tools is a remote MCP server, so any assistant that can add a custom connector by link can use it. Same link, same tools.
Add it to ChatGPT
- 1
Open ChatGPT settings
In ChatGPT, open Settings, then Connectors (called Apps & Connectors on some accounts).
- 2
Turn on developer mode
Under Advanced settings, switch on Developer mode. That is what lets you add a connector by link.
- 3
Create the connector
Choose Create, give it a name, paste the link as the MCP server URL, and save. If it needs a sign-in, ChatGPT asks for it here.
- 4
Use it in a chat
Start a chat, open the tools menu, pick the connector, and ask. ChatGPT asks before it runs a tool the first time.
Custom connectors need a paid ChatGPT plan, and on Team, Enterprise and Edu accounts only an admin can add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in ChatGPT
Add it to Claude
- 1
Open Claude settings
In Claude, open Settings, then Connectors.
- 2
Add a custom connector
Choose Add custom connector, give it a name, and paste the link.
- 3
Connect and use it
If it needs a sign-in, Claude sends you to it. Then turn the connector on in a chat from the tools menu and ask.
Custom connectors are available on paid Claude plans; on Team and Enterprise accounts an admin may need to add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in Claude
https://biz.ossalt.jp/mcpWhat people ask Muse to do
Technical details: safety screening, tools, response time and recent checks
Response time at the last check: 91ms. Worked in 100% of checks over 30 days.
Screening · October 28, 2026
Screened, no issues found
Screening looks for known threats and hidden instructions at the time of the check, and runs again weekly and whenever the tool list changes. It cannot see the server's code, so only connect what you need and review what Muse asks to do. How screening works.
Tools · 13
list_holidaysList 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。ncheck_business_dayCheck 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`/`unverifiedadd_business_daysReturn 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。count_business_daysCount 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。adjust_to_business_dayIf 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。last_business_day_of_monthReturn the last business day of the given month. / その月の最終営業日。to_japanese_eraConvert 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 1989-0from_japanese_eraConvert 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 thalookup_postal_codeLook 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. search_postal_codeFind 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 businesnormalize_addressSplit 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 wlookup_corporate_numberLook 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 (fisearch_corporation_by_nameFind 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 Recent checks
Link
https://biz.ossalt.jp/mcpQuestions about Japan Business Tools in Muse
How do I connect Japan Business Tools to Muse?
Not in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use Japan Business Tools to help me. It is a free service with an MCP server at https://biz.ossalt.jp/mcp. It does not need an API key. Ask me before you share anything with it." Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
Is Japan Business Tools working right now?
At the last check (October 29, 2026, 08:30 UTC) the endpoint was working, answering in 91ms. Over the last 7 days it answered 100% of health checks. It is checked every 15 minutes.
Is Japan Business Tools safe to connect to Muse?
It was screened on October 28, 2026 with the result "screened, no issues found". Screening checks the domain against threat feeds and reads the tools for hidden instructions and requests for passwords or card numbers. It cannot see the server's code, so grant only the access you need.
What can Japan Business Tools do in Muse?
It exposes 13 tools, including list_holidays, check_business_day, add_business_days, count_business_days. For example, you could ask Muse: "Tell me the last business day of this month in Japan so I know when to schedule a payment."
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