# Add Japan National Working Days

> Adds or subtracts dates using the pinned Japan statutory national-holiday schedule and weekend baseline.

- Calculator id: `japan-national-add-working-days` · Category: Everyday Life (`everyday`) · Tool name: `add_japan_national_working_days`
- Canonical page: https://tttkmbb.com/everyday/japan-national-add-working-days · This document: https://tttkmbb.com/everyday/japan-national-add-working-days.md · JSON definition: https://tttkmbb.com/everyday/japan-national-add-working-days.json

## Purpose

Adds or subtracts dates using the pinned Japan statutory national-holiday schedule and weekend baseline.

**Use when:** You need a deterministic Japan statutory national-holiday date offset in 2026-2027.

**Do not use when:** You need company, school, bank, exchange or prefectural closure semantics.

## Example user requests

- Add five Japan national working days after 2027-03-19.


## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `start_date` | date |  | required | Gregorian start date in 2026-2027. |
| `working_days` | integer |  | required | Signed offset; start date is excluded for non-zero offsets. (min -1000, max 1000) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `start_date` | date |  | Input date. |
| `result_date` | date |  | Date reached. |
| `working_days_added` | integer |  | Signed requested offset. |
| `calendar_days_elapsed` | integer |  | Signed Gregorian difference. |
| `national_holidays_skipped` | list |  | Statutory holidays crossed. |
| `territory` | string |  | JP. |
| `territory_name` | string |  | Japan. |
| `day_type` | string |  | Regular weekday, regular weekend or statutory national holiday. |
| `holiday_names` | string_list |  | Japanese statutory holiday names applying on the date. |
| `holiday_kinds` | string_list |  | National holiday or statutory holiday under the Cabinet Office table. |
| `holiday_legal_bases` | string_list |  | Holiday Act or Cabinet Office legal classification. |
| `weekend_days` | string_list |  | CLDR Saturday/Sunday baseline. |
| `calendar_scope` | string |  | Japan statutory national holidays only. |
| `rest_day_policy` | string |  | Company, school, bank and exchange closures are not inferred. |
| `calendar_profile` | string |  | jp-cabinet-office-national-holidays. |
| `dataset_version` | string |  | Pinned Cabinet Office evidence package. |
| `sources` | list |  | Official Cabinet Office and legislation sources. |

## Formula

`move one day at a time; decrement remaining only when Japan national status.is_working_day=true`

Skip the Japan weekend baseline and pinned Cabinet Office holiday dates.

## Data Sources

- Cabinet Office of Japan - National Holidays — https://www8.cao.go.jp/chosei/shukujitsu/gaiyou.html (government, published 2026-09-29)
- Act on National Holidays (Act No. 178 of 1948) — https://laws.e-gov.go.jp/law/323AC0000000178 (legislation)

Data freshness: `static`. Pinned Cabinet Office 2026-2027 package.

## API

- `GET https://tttkmbb.com/api/v1/calculate/japan-national-add-working-days?start_date=…&working_days=…`
- `POST https://tttkmbb.com/api/v1/calculate/japan-national-add-working-days` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/japan-national-add-working-days · OpenAPI operationId `add_japan_national_working_days` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool: `add_japan_national_working_days` (dedicated) or `run_calculator` with `{"calculator_id": "japan-national-add-working-days", "inputs": {…}}`

## Example

- Offset across March 22 statutory holiday: inputs `{"start_date":"2027-03-19","working_days":1}` → `{"result_date":"2027-03-23"}`

```
GET https://tttkmbb.com/api/v1/calculate/japan-national-add-working-days?start_date=2027-03-19&working_days=1
```

## Limitations

You need company, school, bank, exchange or prefectural closure semantics. Skip the Japan weekend baseline and pinned Cabinet Office holiday dates. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Does this resolve employer-specific substitute days?**

No. Only statutory national holidays in the official table are applied.

## Related

- [Japan National Holiday Working Day](https://tttkmbb.com/everyday/japan-national-working-day.md) — Inspect one date and its official legal classification.