Check Japanese holidays and calculate business days for payroll, invoicing and scheduling.
Calculates Japanese holidays and business days using official Japan Cabinet Office data. Helps with payroll deadlines, invoice due dates, and scheduling by excluding weekends, national holidays, and optional banking closures.
Try asking Muse: "How many business days until my invoice is due on July 20th, excluding weekends and Japanese holidays?"
Source: Found in the official MCP Registry (dev.plugrail/jp-calendar) · First listed September 24, 2026
Each bar is one check, every 15 minutes. Green means it answered. Last checked 3 h ago.
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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://jp-calendar.plugrail.dev/mcpNot in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
PlugRail Japanese Calendar is a remote MCP server, so any assistant that can add a custom connector by link can use it. Same link, same tools.
In ChatGPT, open Settings, then Connectors (called Apps & Connectors on some accounts).
Under Advanced settings, switch on Developer mode. That is what lets you add a connector by link.
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.
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
In Claude, open Settings, then Connectors.
Choose Add custom connector, give it a name, and paste the link.
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://jp-calendar.plugrail.dev/mcpResponse time at the last check: 1477ms. Worked in 97.3% of checks over 30 days.
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.
is_holiday指定した日付が日本の祝日（国民の祝日・休日）かどうかを判定します。内閣府公表データに基づきます。入力例: {"date": "2026-01-01"}list_holidays指定した年または期間の日本の祝日一覧を返します。入力例: {"year": 2026} または {"from": "2026-01-01", "to": "2026-06-30"}year は数値（例: 2026。文字列の "2026" は不可）。from/to は YYYY-MM-DD の実在日のみ（例: "2026-01-01"。2026/01/01・20260101 は不可）。year と from/to は併用不可。add_business_days指定した日付(date)の翌日から数えてN営業日目(days)の日付を返します。dateの当日は数えません。daysが負の場合は過去方向（dateの前日から遡ってN営業日目）に計算します。土日・日本の祝日を除外し、calendar="banking"を指定すると銀行休業日（12/31〜1/3）も除外します。dateが営業日かどうかだけ知りたい場合は is_holiday を使ってください（days=0でも同じ情報がskipped経由で得られます）。入力例: {"date": "2026-07-10", "days": 3}business_days_betweenfrom〜to間の営業日数を数えます。既定では「fromを含まず、toを含む」境界です（例:「今日から支払期日まで何営業日か」）。include_from/include_toで境界を変更できます。土日・日本の祝日を除外し、calendar="banking"を指定すると銀行休業日（12/31〜1/3）も除外します。from > to の場合はエラーにせず、from/toとinclude_from/include_toを入れ替えて計算した結果の符号を反転した値（負の営業日数）を返します（反対称則: count(A,B,x,y) = -count(B,A,https://jp-calendar.plugrail.dev/mcpNot in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use PlugRail Japanese Calendar to help me. It is a free service with an MCP server at https://jp-calendar.plugrail.dev/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.
At the last check (November 13, 2026, 13:30 UTC) the endpoint was working, answering in 1477ms. Over the last 7 days it answered 100% of health checks. It is checked every 15 minutes.
It was screened on September 24, 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.
It exposes 4 tools, including is_holiday, list_holidays, add_business_days, business_days_between. For example, you could ask Muse: "How many business days until my invoice is due on July 20th, excluding weekends and Japanese holidays?"
This listing was added from public sources (Found in the official MCP Registry (dev.plugrail/jp-calendar)). If you build PlugRail Japanese Calendar, claim it to correct the details and get your badge.
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<a href="https://musedirectory.ai/connector/plugrail-japanese-calendar"><img src="https://musedirectory.ai/badge/plugrail-japanese-calendar.svg" alt="PlugRail Japanese Calendar on musedirectory.ai" width="236" height="40"></a>