Tokyo is 17 hours ahead of San Francisco during PST, and 16 hours during PDT. When it's 9:00 AM in San Francisco (PST), it's 2:00 AM the next day in Tokyo. Japan does not observe DST.
Tokyo uses JST (Japan Standard Time, UTC+9) while San Francisco uses PST/PDT (Pacific Time, UTC-8/-7).
Challenging time difference! Early morning in Tokyo (6:00 AM - 9:00 AM) corresponds to afternoon in San Francisco the previous day (1:00 PM - 4:00 PM PST).
Tokyo and San Francisco are major tech hubs with strong business ties. Many Silicon Valley companies have offices in Tokyo, and Japanese tech firms maintain significant Bay Area presence.