Komori Onsen is a historic hot spring located in Komori, Kibichuo Town, Kaga District, Okayama Prefecture. It was developed as a therapeutic bathing facility in 1732 (Kyoho 17) by Ikeda Tsugumasa, the lord of the Okayama domain. Legend holds that a heron was discovered healing its wounds in the spring water, and a Yakushi-do temple was built near the source, earning it the name Sacred Spring. The domain invested considerable resources in constructing bathhouses, though the facility was temporarily closed after fresh water infiltrated the source. It was revived around 1953 and continues to operate today as a single-inn hot spring.

The water is classified as alkaline simple hot spring with a remarkably high pH of 9.4. The source temperature is 28.1 degrees Celsius, a cold mineral spring that is heated for bathing. The colorless, transparent water is renowned for leaving the skin silky smooth, and white mineral deposits called yu-no-hana float on the surface. Each bathing room for men and women features two pools at different temperatures, and even the faucets at the washing stations deliver natural spring water in a free-flowing system. The spring is noted for its efficacy against atopic dermatitis, neuralgia, and muscle pain.

Day-trip bathing is available for 600 yen per adult and 450 yen per child. Weekday hours are 11:00 to 17:00, and weekends/holidays 11:00 to 18:00. Overnight stays with two meals range from 9,500 to 11,500 yen per person by reservation. A 2-hour course including mini-kaiseki meal and bathing is available from 2,600 yen. Closed 3-5 times per month on irregular days.