It all depends on where in Tokyo you are, but in general, you are in a very healthy and competitive pool scene. Most likely, you'll find a pool hall near all the major train stations, and most pool halls have an active house pro that plays on either the JPBA tour, or the JBC tour. The other thing nice about pool in Japan is that most rooms are filled primarily with 'players', or people that take the game very seriously. In other words, pool is NOT a very popular dating activity, or drinking activity.
Table time will range from 600-800 yen per hour, but most all pool rooms have an afternoon deal where you play like from 12pm til 5pm for 1,000 yen straight up (typically called 'sukihoudai') or 'all you can play.
The Bagus chain of pool rooms are all over. Roppongi, Ikebukuro, and even up north in Mito and Utsunomiya. The ones in Roppongi and Ikebukuro are very nice classy places with Roppongi frequented by foreigners from all over the world, but both these places lack in what I consider 'players.' And, they're very expensive!
Conditions all throughout Japan are excellent. Most all pool rooms have Brunswick 9 footers, and the places operated by TPCC are stocked with Nagano 9 footers (Japanese knock off of a Brunswick).
None the less, you are fortunate to be within 110-20 minutes from more than 10 rooms with beautiful playing conditions, and most places coodinate their weekly tournaments to avoid double booking with other rooms. So if you do your homework, you can find good tournaments every night of the week.
Have fun..................Wish I was still there.
dave