Appears in the story "The Case of Hidemi and Nanae", which takes place in 1968. Nanae works as a nurse at Hidemi's school and is very interested in her. Nanae's goal is to turn Hidemi into a mermaid and eat her flesh in order to get another studet, Taizou, to fall in love with her. About her connection to Shinobu: Some time after the event with Hidemi, Nanae is shown working at a hospital; she passes on the notebook to Sakura, along with more information than what's written down. After Sakura is turned into a mermaid, Nanae taunts Shinobu with a cure but never reveals it. Later, Sakura reveals that Nanae despises Shinobu because she is Hidemi's daughter. About her connection to the mermaid myth: After Hidemi defeats her, Nanae creates the notebook with the rules and distributes it to students, hoping to eventually find another girl whose last name starts with R (which is quite uncommon). After that, she is shown engaging with other girls, including Hayashi, Sakura and Hiromi. Years later, an adult Hidemi recounts the night when she witnessed Nanae consuming the flesh of Hayashi, a girl who'd been turned into a mermaid but later managed to regain human form. This happened after Nanae recited a variant of the words of the ritual, which caused Hayashi to turn into a mermaid with a fish bottom half — whose flesh grants eternal youth and rapid healing to whomever consumes it; as such, when Nanae meets Hidemi again, she no longer has the scar that Hidemi had given her in self defense, though she still wears a surgical mask over her face. Nanae was good friends with the first mermaid, Shouko, though the two stopped getting along so well after Nanae got a boyfriend and Shouko became jealous that their time together was reduced. According to the lore established by Shouko, Nanae is looking to feed her an "R" mermaid so she can return Shouko to being a human. Whether Nanae was actually interested in Taizou or not, is left ambiguous in the end.