How do ocean currents affect climates in Japan

Japan have moderate climate through out the year as is an island surrounded with sea bodies from all four sides the cold currents from north to south and the hot currents for south to north meet at this island which make the climate of the country moderate it have a wonderful water bodies for fishes and amazing fishing ground for fishers the water bodies also are not so salty as the ocean but the adverse effect is the chances of earthquake or tsunami

It makes the climate flux only in small bits other than that theres no difference