Sana Kurata is a famous 11 year old girl who can't take any more of the class boys "monkey business," so she decides to stand up to Akito the "Boss Monkey" and gain control so she can actually learn.
Sana unleashes the revolt of the girls against the boys but only one of her classmates, Mami Suzuki, will pay the price. Luckily, Sana and her classmates manage to save her. Sana's mother suggests that they find the weak point of the pack leader, Akito to make it clear who's in charge.
Tsuyoshi Oki, Akito's best friend, reveals to Sana that the boy suffers from vertigo, so the girl organizes a bungee jumping competition in the school gym: whoever emits fewer noises during the fall will win the race. Sure of winning, Sana throws herself with the rubber band but, during the flight, she emits a scream, while Akito manages to restrain himself.
Sana realizes that Akito tends to isolate himself more and more and decides to investigate his private life. When she goes to the boy's house, she notices that her sister, Natsumi Hayama, treats him very badly. Furthermore, Akito reacts very badly when his companions make fun of Tsuyoshi because he is "too attached to his mother".
Sana is offered to work in a television drama. Since the plot of the drama is very similar to Akito's experience, Sana thinks that thanks to her acting, she will be able to restore peace between the members of the boy's family.
At the film studios Sana meets Asako Kurumi, the lead actress of the drama, while Rei mysteriously disappears. During the interview for the presentation of the program, the girl sees Akito's father pass by and, after having reprimanded him for his conduct in the family, she asks him to see the show on TV. When Sana goes to the boy's house to make sure the Hayama family is watching the play, she notices that Akito is not there and goes to look for him.
Asako Kurumi asks to be able to do an interview with Sana. The latter realizes that every time she meets the actress, Rei suddenly disappears. Eventually the girl understands the reason for these disappearances.
Sana distances herself a little from Rei because she fears that he will abandon her to be with Asako. Sana goes on a field trip with her class to visit the town hall.
Rei learns what happened to the trip and has Sana's mother summon Akito, hoping that the woman will give him a good wash of the head. Instead, she just wants to figure out if her daughter's friend is a good guy. Asako, on the other hand, decides to go to Sana's house to clarify her relationship with Rei.
Sana is convinced that Rei is her first love and that he confides everything to her. Misako, Sana's mother, believes that her daughter should open her eyes: Rei is a regularly salaried collaborator and is an adult who, as such, also has a private life that Sana is not required to know.
Akito's father feels bad. Akito and Sana, during this story, show themselves very united and help each other. Sana manages to get Rei and Asako to meet.
Due to busy work commitments, Sana forgets to go to Hisae's birthday, one of her classmates. The girl and her friends are very offended by this gesture.
The class participates in a trip to the mountains. During the evening Sana and Akito get lost and he takes the opportunity to ask her what troubles her.
On the last day of her vacation, Sana takes part in a theatrical performance to which her friends are invited as spectators. Here Naozumi and Akito know each other. The former tries to make Akito feel inadequate: since the latter does not have a hobby, he cannot be the ideal guy for Sana. From this moment on the boy will decide to devote himself to karate.
Misako's home is under siege by reporters and Akito decides to host Sana at his home until the waters have calmed down. Here the girl joins Natsumi who reveals embarrassing information about her brother.
Sana, Akito, Miho Obana and Zenjiro's manager participate in a quiz conducted by Babbit and Zenjiro, with questions based on the first nine episodes of the anime. Clips extracted from the above episodes are shown. (Episode filler)
