What this document is
Proof of WHY your relative must stay longer. Immigration only extends a short stay for a genuinely unavoidable reason (illness, childbirth, a hospitalised family member…) — this is the deciding document.
What it must show
- Matches the reason: illness → 診断書 (doctor's certificate stating the treatment period)
- Childbirth / childcare → 母子手帳 or the baby's birth certificate
- Hospitalised relative → their admission / medical certificate
- Shows clearly until WHEN the stay is needed
Where to get it
The hospital / clinic giving treatment (診断書) · the city office (the baby's birth record).
How to get it
- Ask the doctor to state the condition + how long treatment / care is needed
- Add a one-page note in Japanese explaining why the person cannot leave on time