Kōan has two campgrounds on the lake, this one on the northeast corner has fine Fuji views, a jacuzzi, a helpful English-speaking owner and an attached restaurant and shop, as well as three cabins should you not wish to camp. Reservations are not required (nor accepted) for camping; just show up.
Having a car is the most convenient way to get to Kōan Motosu Inn. At time of research, only one daily bus (10.18am, 50 minutes) from Kawaguchi-ko Station comes here, returning at 1.47pm.