Can I go to South Korea with a Japanese tourist visa?

Divided into places. First of all, passports and visas are different. You hold a Japanese passport and you hold a Japanese visa are two different concepts. Holding a Japanese passport to go to South Korea is visa-free, but holding a Chinese passport and a Japanese visa is of no use. Whether you are visa-free or not depends on the passport, not the visa. Only Jeju Island in South Korea is visa-free for Chinese passports, while other places such as Seoul require visas.

Also, the relationship between China and South Korea is not very good recently, so be careful when traveling to South Korea