About StayDays

Why it was made

People preparing for Japanese permanent residence or UK settlement keep asking the same question in forums: how many days was I really outside the country, and in which 12 months? Many count passport stamps by hand or build a spreadsheet whose assumptions nobody can see. The Japanese guideline revised in October 2026 describes absences over a 10-year window, which means a long count. StayDays counts the days and keeps the assumptions on screen.

Who runs it

Eddy Hwang, an individual. Not a lawyer, 行政書士 or immigration adviser, and not connected with the Immigration Services Agency of Japan, the Ministry of Justice or the UK Home Office. Contact: eddyhwang.kr@gmail.com

How it calculates

• Dates are handled as whole calendar days, so time zones do not shift results.
• Japan: you choose whether the departure and return days count; the default counts both.
• UK: only whole days outside count, and every 12-month period ending on a day in the qualifying period is checked.
• The calculation code has automated tests for month ends, leap years, the six-month boundary and the Home Office day-181 example.

Sources (checked 2026-10-31)

• Immigration Services Agency of Japan, 永住許可に関するガイドライン (revised 1 October 2026)
• Immigration Services Agency of Japan, 永住許可申請 (permanent residence application)
• Ministry of Justice of Japan, 国籍Ｑ＆Ａ, Q9 and Q10
• Immigration Services Agency of Japan, 出入（帰）国記録の開示請求について (requesting your entry and departure records)
• GOV.UK, Immigration Rules: Appendix Continuous Residence
• Home Office, Continuous residence caseworker guidance (version 10.0, published 8 October 2026)

When a rule changes, the sources are re-read and the counter and guides are updated. If you spot an error, please email.