My son is going to be visiting Japan with three of his American friends
and will be in Tokyo between Jan 5-8th, and Kyoto Jan 8-9th. I thought
it would be fun for him to experience an idol/otaku/etc related event
while he was there.  Anything to recommand?

Of course general Tokyo suggests would also be appreciated.

-- 
    the value of a world model is not how accurately it captures reality
    but how often it leads us to take appropriate action