I went to the Okazaki city gym yesterday (Friday evening), and made use of the facilities with some friends. The entrance was ¥200, but I think I might get a monthly pass (¥2040) and go more often. The gym is one road to the east of 248 north of AEON.

The facilities are pretty small, but even the larger gyms near here have a very small weight machine section, nothing like 24 Hour Fitness or the CU Rec Center.