All dates stored in UTC, so if any other country raised a ticket, we just told them to update their timezone in their profile, and the client was happy. Japan is the only country that this required incident reports.
Sounds like a pain in the ass. I would just build the incident report form to have the option "Date/times are all wrong", and when you see the user is from Japan and selects this drop down option, check if their timezone is set correctly, and if not, reset it to JST...
Then the form would prompt them "Are you sure, please look again", and most of the time the problem will have disappeared, right?
