Akiko moves into a school dormitory with her brother Akito, when he transfers to her school. Owing to her brother complex, Akiko has a crush on Akito. With both of them in student government, will Akiko be able to share him with the other council members?

Akito catches Akiko reading a trashy romance novel. Akito, having trouble settling in to in his class, is given firsthand lessons in the concept of "tsundere"from both Akiko and Anastasia. Akito and his longtime friend Ginbe get into an argument.

Akiko asks Akito for help changing her light. Akito has his hands full maintaining the dorm, from fixing the plumbing to repairing the doors. The girls have differing opinions over allowing Akito to take in the laundry. Akito helps Anastasia settle in.

Akito brings home a special dessert, just for Ginbe to enjoy. Akito continues to fix up Anastasia's room, and the two of them discuss her hobby of collecting stuffed animals. Arashi has the girls take a bath together, to help them bond together better.

In a student government meeting, the council members discuss what they are going to call Akito. Kaoruko proposes that Akito write a short story to be published in a women's magazine. She grows concerned for him when she learns his sibling is a sister.

Kaoruko reads the latest installment of Akito's love story. She decides to stop by the dorm, where she meets the others, and asks them whether they think Akito has a sister complex. The council decides to separate Akito and Akiko into separate rooms.