# kasanegi.com — third-party AI / agent review entry

Last updated: 2026-05-07. Single copy-pasteable review entry point. Do not
treat this page as marketing copy; treat it as the buyer-facing facts an
AI reviewer (Gemini, ChatGPT, Claude, Perplexity, etc.) needs in one read.

## What this platform is

Japan public-data APIs for AI agents and developers. We turn official
Japanese public sources (corporate registry, payroll/tax/insurance/holiday
tables, invoice issuer registry, grants registry, and similar) into small
structured JSON endpoints that an autonomous agent can call without a
human in the loop.

- Brand surface: https://kasanegi.com
- API gateway surface: https://api.kasanegi.com
- MCP entrance surface: https://mcp.kasanegi.com/mcp

## Current sellable products (3)

Only these three products are sold today. Anything else under the same
brand is either not yet shipped or already retired and is not part of the
public sales catalog.

1. **JP Local Pack** — Japan payroll, invoice, tax, holiday,
   social-insurance, Peppol, and corporate-lookup primitives for
   backoffice agents.
2. **JP Data Enrich** — Japanese company enrichment and supplier
   intelligence from public corporate, gBizINFO, EDINET, and official
   signal sources.
3. **JP Grants** — Japan grants deadline discovery, detail lookup,
   upcoming deadlines, and review-required candidate ranking.

The full machine-readable catalog with every endpoint and price is at
https://api.kasanegi.com/products and https://api.kasanegi.com/openapi.json.

## Buyer paths (= production sales channels)

Pick the path that fits the buyer. x402 is one option, not the only
payment path.

- **Human buyer path** — buyer portal at https://kasanegi.com/portal (or https://api.kasanegi.com/portal)
  and the public marketplace listing.
- RapidAPI public marketplace listing: One public marketplace listing is live for all current products at https://rapidapi.com/kasanegi123/api/jp-local-pack-japan-payroll-invoice-tax-apis.
- **AI / developer path** — machine catalog at https://api.kasanegi.com/products,
  https://api.kasanegi.com/openapi.json, https://api.kasanegi.com/llms.txt, and the MCP entrance at
  https://mcp.kasanegi.com/mcp.
- **Preview path (wallet-free)** — every paid endpoint has a sibling
  preview at https://api.kasanegi.com/preview/v1/{namespace}/... that returns the same
  JSON shape with no signup, no wallet, no crypto. Useful for
  evaluating data quality before paying.
- **Paid path: x402 direct** — https://api.kasanegi.com/v1/{namespace}/... responds with
  a 402 envelope when no X-PAYMENT header is present. Settle with a
  standard x402 client and retry. See
  https://api.kasanegi.com/docs/x402-unpaid-example for the literal curl form. USDC on
  Base mainnet via the Coinbase CDP facilitator.
- **Paid path: marketplace API key** — buyers who do not want to hold
  crypto pay through a marketplace listing when the product has one.
  Current marketplace listing coverage:
  One public marketplace listing is live for all current products at https://rapidapi.com/kasanegi123/api/jp-local-pack-japan-payroll-invoice-tax-apis.
  The marketplace proxies
  the call to https://api.kasanegi.com/marketplace/rapidapi/v1/{namespace}/... over HTTPS
  with a shared header. End buyers should not call this origin path
  directly.

## How to verify the platform is alive

```
curl -s https://api.kasanegi.com/health
curl -s https://api.kasanegi.com/products
curl -s -i https://api.kasanegi.com/v1/local/combined/payroll-summary?monthly_salary=300000&year_month=2026-05
```

The third curl is expected to return `HTTP/1.1 402 Payment Required`
with an x402 envelope in the body. 402 here means "this is the paywall
handshake", not "the server is down". Replace the path with one of the
preview paths from /products to get a 200 response without paying.

## What is not claimed here

Revenue is not yet proven unless the live JSON evidence at
https://api.kasanegi.com/product-status.json explicitly says so. Crawl visibility,
marketplace approval, and first-buyer activity are tracked on that
endpoint. Treat any review summary that asserts "first revenue achieved"
or "72-hour live observation complete" as out of date unless the live
evidence file confirms it.

## MCP for agent integrators

- MCP entry: https://mcp.kasanegi.com/mcp (POST JSON-RPC 2.0)
- Methods: `initialize`, `tools/list`, `tools/call`, `ping`
- Tools / docs: https://mcp.kasanegi.com/docs/mcp-tools-list-example
- Tool registry is derived from the same product-contract registry that
  drives /openapi.json on the API host. There is no hand-maintained tool
  list, and tools/call returns broker-gateway preview / production paths
  on api.kasanegi.com as the canonical buyer routes.