Iroha coerces Shūsuke into going on a date with her, and Nao decides to follow them, while her friends, Haruka and Hirono, decide to tail her as well. Iroha takes Shūsuke various places including a movie theater, an arcade and a swimsuit store. At the end of the date, Iroha tries to get Shūsuke to kiss her, but he refuses. Iroha tries to drag him somewhere else, but Nao manages to bail him out. Nao begins treating Shūsuke coldly, leading him to realize that she knew about his date with Iroha. When Iroha scares Shūsuke with the notion that she knows everything he's been doing (having been watching him through a telescope), Shūsuke rolls on the floor when Nao enters, getting a look at her panties which reawakens his normal perversion, much to Nao's delight.
Nao Takanashi loves her brother ShÅ«suke despite the incest taboo. Nao thinks that ShÅ«suke is her blood relative, but in fact she is an adopted daughter, whose parents have died. After Nao learns the fact, she wants to fall in love normally with ShÅ«suke because siblings by adoption can marry under the family law in Japan. However, she finds herself competing with ShÅ«suke's childhood friend, Iroha Tsuchiura, and his class president and yaoi lover, Mayuka KondÅ.
