Have you been before?
It's amazing. The food is amazing. Tokyo is very nice. Kyoto is very temple-filled and cultural. Nara is like a small Kyoto, but with bigger temples. Hiroshima is very humbling and has the best okonomiyaki ever. The food is amazing. If you speak the language, everyone is interested in starting a conversation. And some of the weird things there end up being wonderful experiences.
Oh boy, okonomiyaki. That stuff is amazing. My sister-in-law is from Hiroshima and my brother lived there for ~4 years. Hiroshima is also one of my favorite cities to run in. Thinking about this really makes me want to go back soon :-) I'd love to see Kyoto and Nara now as well.
Most of the reason to go to Kyoto and Nara is the culture. They have so many temples, which never get boring, and have heaps of awesome deer. There's just something about drinking from a spring which has been going for thousands of years that is very awesome. Now I want to go back too...