Besides that gym, there are several other public ones that people at school use, especially Momochi Taiikukan, where some students go to play badminton a few times a week. In the summer, many people go jogging in the huge park Ohori Kouen (although since I don`t have a car I have no idea where I would put my stuff). Other activities people do are jiu-jitsu, bouldering, and hiking. It`s best to ask students around and see what they do and join their activities. Or you can ask your Japanese friends. It`s a great way to meet new people!