All of Japan is in the same time zone, from Hokkaido down to Okinawa in the south. Japan is in a time zone referred to as "Japan Standard Time"(JST), which is 9 hours ahead of Greenwich Time. It is 17 hours ahead of Los Angeles, 14 hours ahead of New York, and 9 hours ahead of London. (During the summer, the difference is one hour less). There is a one-hour time difference with Beijing, but Korea is in the same time zone.
Daylight Savings Time is not observed in Japan, so there is no seasonal time change.
For your convenience, some pages on the Tokyu Hotels website feature a clock like the one on the top right corner of this page.