Even at the age of 70, Seiji's libido is still strong, and he is sexually intrigued by his grandson's wife, Hana, with whom he lives. Seiji, a former university professor, quotes from Western literature, his specialty, to insist that sex is a wonderful act, but Hana just looks down in embarrassment. One day, by chance, Seiji realizes Hana's secret sexual urges and sets a trap for her...