Koumi Sasaki, a woman with a voluptuous body and a highly sensitive personality, plunges into a mixed-gender hot spring. The hot spring, which springs from the riverbank, does not have a changing room. As she spreads her legs in an M-shape or crawls on all fours, her breathing gets rougher and rougher. She becomes more and more immersed in the pleasure of being watched, and writhes in pleasure, showing the man glimpses of her private parts.
