A historic public bathhouse established in 1934 (Showa 9), located at the foot of the Hitoyoshi Castle ruins in Hitoyoshi City, Kumamoto Prefecture. Legend has it that the founder had a dream of hot spring water gushing forth, which inspired him to excavate near the castle ruins, where he successfully discovered the spring source. The Hitoyoshi Basin, approximately 30km east-west and 15km north-south, has a unique climate with morning fog occurring over 100 days per year. The spring quality is sodium-bicarbonate/chloride spring (hypotonic weakly alkaline high-temperature spring) with a pH of 8.0. The source water at 48.1 degrees Celsius is delivered as 100% free-flowing from the source with absolutely no added water, heating, circulation, or chlorination. The slightly yellowish-brown water has a silky smooth texture and is known locally as a 'beauty spring' for its excellent skin-beautifying effects. Small brown mineral deposits float in the bath, and the water has a distinctive aroma blending gypsum and moor scents. Drinking the spring water is also available. The facility features a simple design with only small stone indoor baths separated by gender, but after sustaining flood damage during the July 2020 Kumamoto heavy rains, it reopened in October 2020 with renovated flooring and additional showers. Among the 22 public bathhouses in Hitoyoshi City, Motoyu is considered one of the most representative. At just 300 yen for adults, it offers an exceptional authentic free-flowing hot spring experience.