•You can apply up to 3 months before expiry. If you apply before the expiry date, you may continue living in Japan during the review period (tokureikikan — valid until the disposition date or 2 months after the expiry date, whichever comes first)
•Applying after the expiry date may result in an overstay violation — start the process early
•The fee (¥6,000 at the counter / ¥5,500 online) is paid after approval, not at the time of application
•Online application requires prior user registration on the ISA online system
•A Juminhyo (resident certificate) is not on the standard submission list, but some regional immigration offices may request it — having one ready is advisable