Miyako Kaneshiro lives alone in a house like a hot spring inn. She used the holiday to have her son, his wife, and their grandson come home, but Miyako stubbornly refused to bathe with them. Miyako had a tattoo on her chest that she wanted to keep secret from her family. However, her grandson Yuuto found it, and instead of rejecting the tattoo, he became sexually aroused and ended up having a physical relationship with Miyako. In one night, Miyako was captivated by the intense sexual desire of the young man.
