Heading to Japan in January for 2 and a half weeks, Will be in Niseko snowboarding for 5 nights and then spend the rest of the trip on the main island. 2 nights in Tokyo, 2 in Kyoto, 2 in Hiroshima and then 4 nights in Tokyo at the end. Just wondering if anyone has some hidden gems to check out whilst over there? I would like to check out the tuna auctions but I hear you have to get there real early before the trains start running? Also would love to catch a Sumo match if possible.
Any suggestions?

Cheers