https://ubuyama-kanko.com/lan/en/#yamabuki

“Yamabuki Suigen” was selected as one of the 100 best waters of Kumamoto. About 30 tons of water flows out every minute, and the water temperature is always at 13.5 degrees. It can be reached by a 10-minute walk from the parking lot. 

A hot spring town spreads along the Manganji River. There are three lodging facilities. There are 3 public baths. Manganji Onsenkan, an open-air bath (kawayu) along the river, and a hot spring located 100m upstream of this river. Kamiyu became a men-only bath when the Manganji Onsenkan was rebuilt.