I'm heading over to Japan to the main island of Honshu in September and was wondering if anyone on here has climbed in Japan and can recommend crags?
At the moment we're looking at Ogawayama for climbingt: http://www.ogawayama.com/
Ogawayama is fantastic - lovely spot with some excellent climbing on granite. I've camped and climbed there 3 or 4 times, and would go back again in a heartbeat. You've found the right guide online - I made a pdf version of that which I can send you if you want (email me).
Other areas within striking distance of Tokyo are Jogasaki, Yugawara, and Joyama - all worthwhile. The first is seacliff climbing, steep and pretty hard. Yugawara has a range of stuff from easy to hard on andesite, overlooking the sea. Joyama is inland, and has some longer and more adventurous stuff - great spot.
See http://www.tokyoclimbing.com/ for some more info on these and other areas. Your best bet is to get to one of the climbing walls in Tokyo mentioned on this site, and go chat with some of the western climbers (the Japanese climbers are very friendly too, but not many speak English) - the expat scene is friendly and helpful, and you will almost definitely be invited to climb with them.