I am travelling to and from Jakarta (from the US) this December, and have long layovers both ways through Tokyo (changing airports).
Layover #1 - 13 hrs, need to switch airport from Narita to Haneda. Lands 8:30pm, departs at 10am.
Layover #2 - 12 hrs, need to switch airport from Haneda to Narita. Lands at 11pm, departs at 11am.
Both layover lands on a Friday, out on a Saturday. Taking into consideration time for immigration, customs, baggage, and travel to/from the airports, I figured, we'll have about 6 hours to wonder around Tokyo. A good bit of that time will be in the late night/early morning part of the day. Assuming we don't land and want to immediately pass out, is there anything to go see or do, say around 2 am in Tokyo?
Definitely have eyes set on Tsukiji Market. EDIT: Any other ideas of things to do between midnight and 6am in Tokyo? Figured I'd give crowd sourcing a try :)