Do you have a favourite artist? Well, if they are having a concert or festival in Japan, go then. It's that simple. That's all I have to say. If you have a season that you want to visit Japan in, go then. If you want to go skiing, go to the northern areas in Winter! If you have a certain temperature or rainfall that you would like to visit Japan in, checkout our page all about the temperature and rainfall in Japan: Climate! Wait, you want more information? Okay, I'll cook something up as a guide.
skiing and other snow activities
cherry blossoms
art
alpine hikes
fireworks in Tokyo
hiking through autumn foilage
if it's a popular time to go, the prices will be higher
hailstorms can smash car windscreens, meaning that if it's hailing, you could have a hefty fee to pay!
if it's raining, you will not be able to enjoy much of your time in Japan