I've never been to Japan, let alone rode a bike there.
Sometimes my activities upload with the correct time zone. Sometimes they upload with Japan Standard as the time zone. I live in Adelaide, 35 degrees South of the equator. Japan is 35 degrees North of the equator at the same longitude.
My Edge 520 downloaded a new time zone map recently, but that doesn't seem to have fixed it.
Strava has the correct time applied, just Garmin Connect is wrong. Easily fixed, but annoying to have to do it on 50% of my rides.
I'm syncing through my phone. USB still had the same problem sometimes, so I conclude it's Garmin Connect.
Anyone else have similar problems?