Connect Corporate Number Publication Site (Houjin Bangou) to Claude Code
Query Corporate Number Publication Site (Houjin Bangou) directly from Claude Code. Arlet links the two through one MCP connection and takes care of API keys.
This server connects your AI client to the Corporate Number System Web API (Version 4) operated by Japan's National Tax Agency. Every registered corporation in Japan has a unique 13-digit corporate number, and this API is the authoritative source for the mapping between numbers, registered names, and head-office addresses.
Key features:
- Search corporations by name (prefix or partial match), optionally narrowed by prefecture/municipality.
- Resolve up to 10 corporate numbers at once to their registered name, address, corporation kind, and change/closure history.
Because the corporate number is the common key used by gBizINFO, EDINET, procurement data, and most other Japanese business datasets, this API is the natural first step for entity resolution: find the right corporate number first, then join everything else onto it.
Using the API requires a free application ID (アプリケーションID) issued by the NTA; apply on the Web API page of the Corporate Number Publication Site. Set it as HOUJIN_BANGOU_APP_ID in your Arlet environment variables.
How to connect Corporate Number Publication Site (Houjin Bangou) to Claude Code
- 1
In the Arlet dashboard, open Data tools, find Corporate Number Publication Site (Houjin Bangou), set the API key issued by Corporate Number Publication Site (Houjin Bangou) and switch it on.
- 2
In your terminal, run claude mcp add --transport http arlet https://mcp.arlet.dev/mcp/ to add Arlet as an MCP server.
- 3
Start Claude Code, run /mcp, select arlet and click Authenticate.
- 4
Your browser opens. Sign in with Google and click Allow on the consent screen. The connection is complete.
The connection is per user and works across every project on the same machine.