For Microwave popcorn, I just buy bags of kernals.
Put a tablesppon or so in a paper lunch bag with a little salt. fold over top of bag.
2 minutes (YMMV) and popcorn is ready
Can add other stuff as needed.
Tokyo - Robot restaurant- love the Shinjuku area at night.
Akihabara for Electronics.
Asakusa for old Tokyo temples and feel.
Kyoto - the rice temple and the giant bamboo forrest, great older buildings, very touristy. Bullet train from Tokyo big station, the Tokyo station also has a big Ramen hall- If only US stations had so much good food.
Sushiro Sushi - fun watching sushi go by on a lower conveyor belt, special orders on an upper belt that goes really fast!
Fukuoka Budha - it's a bit of a train ride, past Yokohama, but is old country side Japan.
The game rooms , usually second or third floor, marked out by big signs with the Game developers names. Games you will not see outside of Japan.