Do I need a visa to transit Japan when I have a US visa?

No need. According to the regulations of the Japanese Embassy in China, Chinese citizens holding a U.S. visa when transiting through Japan must hold a U.S. visa within 90 days, have a tourist visa from a Japanese government-designated travel agency, stay in Japan for no more than 72 hours, and hold a valid If you have a return ticket and sufficient payment methods such as cash or credit card, you do not need to apply for a visa.