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jp-calendar

MCP serverProductivity

jp-calendar gives your AI accurate knowledge of Japanese holidays and business days, drawn from official Japan Cabinet Office data. Once added, your AI can check dates against the Japanese calendar, count working days, and schedule around holidays. This keeps plans and deadlines aligned with Japan's official calendar.

Use jp-calendar in Claude, ChatGPT or Ahel Desktop

Free. Sign in, add jp-calendar and connect your AI. About a minute.

ClaudeChatGPTAhel Desktop

Also: Claude Code · Cursor · Codex

Then ask your AI: use the is holiday tool from jp-calendar

Details

Available today. Use it from your connected AI after setup.

Add jp-calendar, then ask your AI a date question, such as whether an upcoming day is a Japanese holiday or how many business days a task will take.

jp-calendarStart free

What your AI can do with it

  • Check whether a specific date is a Japanese holiday
  • Count business days between two dates
  • Find the next business day after a given date
  • List Japanese holidays for a given period
  • Plan deadlines and schedules around Japanese holidays

Install jp-calendar

The server’s own address, for the clients that take one directly. Or connect Ahel once and every client you use reads it from one address, with the account kept on Ahel rather than in each client’s config.

  • Claude Code

    claude mcp add --transport http --scope user jp-calendar 'https://jp-calendar.plugrail.dev/mcp'

    Run it once in your project, then open /mcp to approve any sign-in the server asks for.

  • Claude Desktop

    https://jp-calendar.plugrail.dev/mcp

    Add a custom connector in Settings, paste this address, and approve the sign-in.

  • Cursor

    cursor://anysphere.cursor-deeplink/mcp/install?name=jp-calendar&config=eyJ1cmwiOiJodHRwczovL2pwLWNhbGVuZGFyLnBsdWdyYWlsLmRldi9tY3AifQ==

    Open the link and Cursor adds the server at that address.

  • ChatGPT

    https://jp-calendar.plugrail.dev/mcp

    In Settings, enable Developer mode, create an MCP app, and paste this address. Your plan and workspace must allow custom apps.

  • Codex

    codex mcp add jp-calendar --url 'https://jp-calendar.plugrail.dev/mcp'

    Run it once, then sign in with codex mcp login jp-calendar if the server asks for an account.

From the project's README

As published by plugrail/servers in README.md. This repository publishes several servers, so only the opening is shown here.

A collection of MCP servers that connect to Japanese public data. The name alone does not describe the project, so plugrail is not related to railways or railway services.

Live servers

ServerMCP endpointToolsStatus
jp-calendarhttps://jp-calendar.plugrail.dev/mcpis_holiday, list_holidays, business_days_between, add_business_daysLive

Connect

See the jp-calendar connection guide.

Self-hosting

  1. In packages/servers/jp-calendar/, copy wrangler.example.jsonc to wrangler.jsonc and fill in your Cloudflare resource IDs.
  2. Create the D1 database and KV namespace referenced by that configuration.
  3. Run pnpm --filter @plugrail/jp-calendar deploy.

The self-hosted server runs independently. Authentication, rate limiting, and usage metering are features of the hosted service only.

Architecture

Shortened here. Read the whole README on GitHub.

Tools it offers (4)

What this server listed when Ahel dialed its public endpoint in Oct 2026, with no key and no account of yours. The names are the server’s own.

  • is_holiday
  • list_holidays
  • add_business_days
  • business_days_between

Signals

Last commit
Oct 2026
Advanced
Delivery
jp-calendar MCP server → your Ahel connector (mcp.ahel.ai) → your AI.
Item type
mcp-server
Key
dev-plugrail-jp-calendar
Source
github.com/plugrail/servers
Hosted endpoint
https://jp-calendar.plugrail.dev/mcp

github.com/plugrail/servers

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