San Diego is typically 17 hours behind Tokyo. When it's 9:00 AM in Tokyo, it's 4:00 PM the previous day in San Diego. Japan does not observe daylight saving time, but San Diego does.
During US daylight saving time (March to November), the difference is 16 hours. During US standard time (November to March), the difference increases to 17 hours.
Optimal meeting window: 4:00 PM - 7:00 PM San Diego time (8:00 AM - 11:00 AM Tokyo next day, or 9:00 AM - 12:00 PM in winter). Late afternoon San Diego catches morning Tokyo.
San Diego has a significant Japanese influence, with a large Japanese community and the famous Friendship Garden in Balboa Park. The biotech and defense industries in San Diego have growing connections to Japanese companies.