@Raymond Lin if you were in Tokyo for like....12 hours 7pm till next day 9am - what would you do/stay?
Depends....
Does the clock starts at Shinjuku or are you in Narita or Haneda Airport at 7pm?
Because it will take about 35-45mins from Haneda into the city and about 2hrs from Narita.
Do you need to be back at the airport (and which one) at 9am or are you leaving say Shinjuku at 9am?
And how much sleep do you need?
Are you alone?
Note that the trains stops from midnight, the last train to and from the airport is probably around 10:30 from Narita. Late night (like past midnight buses to and from the airport are currently suspended). Although you can get a taxi to Haneda for about £30-40. Narita will set you back a couple of hundred.
Things to do in the city, most retail shops starts closing at 8pm/9pm. Most restaurants closed by 10pm. Some opens 24hrs, like Matsuya and Sukiya. Konbini like 7-11 are mostly 24hrs.
Late night entertainment you can do Karaoke, but room are booked by the hour. The bars around Omoide Yokochō would start closing from around Midnight. There are Manga Cafes you can go to that stay overnight.
Shibuya Sky closes at 10:30.
Basically, if you can get to Tokyo shops by 7pm, I would go get a good meal, perhaps go to Shibuya at 9pm to check out the city view. Then on if you want to go drinking then you can go to a bar. If you want to stay up all night then it's Karaoke.
A budget night sleep i would look at APA hotel, avoid Capsule hotels, they are not that fun really. Plus the prices has gone up since all the tourists started using them. They are loud, the temperature is hard to control, or there are none. APA is a hotel chain targetted for businessmen. Tiny room but at least your own bathroom.