The chapter opens with a flashback to the events of the previous chapter. The narrator explains that he is now married to a woman named Wagatsuma, who is also known as "San" or "Waga-Tsuma." She is a member of the university's science club, and she and her twin sister have been confined to a ball and a chain dungeon for the past nine years. They have escaped from the dungeon and have returned to school. The chapter ends with the narrator asking what his wife thinks of him.