PlugRail Japanese Calendar

dev.plugrailPublished by plugrail.devOfficial publisherv0.2.0Updated Oct 28, 2026

Japanese holiday and business-day calculations using official Japan Cabinet Office data.

VerifiedStreamable HTTPWeb executableProductivity & WorkflowData & Analytics

Overview

AI-generated overview

Remote MCP server that lets an assistant check Japanese public holidays and count or add business days using Cabinet Office data.

What you can do
  • Check whether a given date is a Japanese national holiday
  • List Japanese holidays for a year or a date range
  • Add or subtract N business days from a date, skipping weekends and holidays, optionally excluding bank closure days
  • Count business days between two dates with configurable inclusive boundaries
When to use it
Useful when scheduling or planning around Japanese holidays and working days, such as setting deadlines, payment dates, or delivery estimates that must fall on a business day in Japan.
Requirements
A remote MCP endpoint; no authentication, environment variables, or headers are declared. Network access to the hosted service is needed.
Before you install
The service is not an official government service and its data is not guaranteed by any Japanese public body. The hosted endpoint may apply authentication, rate limiting, and usage metering; self-hosting requires your own Cloudflare D1 and KV resources. Results are read-only lookups.

Installation

In SourceWeft

  1. Open PlugRail Japanese Calendar in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/dev.plugrail%2Fjp-calendar/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "plugrail-japanese-calendar": {
      "type": "http",
      "url": "https://jp-calendar.plugrail.dev/mcp"
    }
  }
}

README

plugrail

[License: MIT] [MCP]

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

text
MCP client    |    vjp-calendar Worker --> Cloudflare D1 (holiday data)                   --> Cloudflare KV (cached data)

Sources and disclaimer

This is not an official service of the National Tax Agency, the Digital Agency, or any other Japanese government body. Information provided does not represent their official views and is not guaranteed by them.

Source: Adapted from the Cabinet Office "National Holidays" page (https://www8.cao.go.jp/chosei/shukujitsu/gaiyou.html)

Contributing

Issues and pull requests are welcome. Please include enough context to reproduce a problem or explain a proposed change.

License

MIT. See LICENSE.

Source: README.md at commit 1cccfd6

Tools

4

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"}

Parametersdaterequired

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"}

Parameterstofromyear

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}

Parametersdaterequireddaysrequiredcalendarextra_closed_dates

business_days_between

from〜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,y,x)。A≠B、すなわちfrom≠toの場合に成立する恒等式で、from===toはこの分岐に入らないため対象外）。入力例: {"from": "2026-07-10", "to": "2026-07-20"}

Parameterstorequiredfromrequiredcalendarinclude_toinclude_fromextra_closed_dates

Version history

2
  1. v0.2.0LatestOct 7, 2026
  2. v0.1.1Sep 16, 2026

Score

100% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

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