Kotohikihama Rotenburo

A small outdoor bath at Kotohiki Beach on the Sea of Japan coast, essentially a natural open-air pool right by the shore. The water runs warm and smooth with a faint mineral smell. Reviews mention it as a free spot useful for warming up after swimming, and a foot bath version is available in summer. Simple and unpretentious, it is the kind of place you find at the beach and are glad exists.