A highly contagious incest virus induces several generations of a Japanese family to have sex in all possible constellations and across gender boundaries – and with that man in a bear costume who suddenly appears? Only in Japan!

A boy who lives with his parents in Kyoto comes to Tokyo for a business trip and stays with his fuck buddy. They have no special plans for the five days together. They will go to work in the morning, come home, spend the evening together, and sleep. The first night when he arrives, the fuck buddy starts to have sex with him just as usual, but he is somehow unable to respond. In fact, he has been concerned about a certain thing since before he visits Tokyo.