Japan’s typhoon season runs roughly from July to October, when storms spin up over the warm Pacific and curve toward the archipelago. This map tracks tropical cyclones active near Japan using data from the Japan Meteorological Agency (JMA). Outside the season you’ll usually find a calm, empty ocean here, which is exactly what you want to see.
A note: this page is for information, not emergency response, and it is not an official warning system. If a typhoon is approaching while you’re in Japan, check JMA and NHK forecasts and follow local guidance, especially before any coastal or island travel.