Miki's parents decide to get a divorce and swap partners with the couple they met while on vacation. The couple's son Yuu is attractive but strange.

Miki panics as Yuu almost reveals the family secret during an interview at school. Her childhood friend Ginta gets annoyed at Yuu's presence.

Miki and Yuu's parents throw a barbecue to celebrate their children's safe return. Miki gets angry when her father suggests going on a family outing.

Miki keeps thinking about the mysterious girl next to Yuu in the photo she accidentally found. Yuu and Miki go on a semi-date to a theme park.

Miki gets upset with Ginta for kissing her. When she spots Yuu's ex-girlfriend Arimi at the school gate, she uses her to get away from Ginta.

Ginta's confession only serves to frighten his crush. Yuu makes a fool of Ginta, then upsets him even further when he walks into the house after Miki.

Yuu agrees to keep quiet after discovering Meiko's secret. Ginta's cousin Tsutomu shows up to participate in a tennis game at his school.

Miki joins Yuu and Ginta after getting separated from her group during the school trip. Arimi asks Ginta to pretend to like her to make Miki jealous.

While helping Yuu at his part-time job, Miki realizes that he has many admirers. Ginta, Arimi and Tsutomu all show up at the store and cause drama.

Miki and Yuu spend a day shopping and eating together when they get the house all to themselves while their parents go on vacation.

When Yuu's mother calls to wish her son a happy birthday, Miki goes all out and puts together an impressive feast to help him celebrate.

Ginta says that he'll stop seeing Arimi if Miki chooses to be with him. Miki gets chosen to represent her school in an upcoming tennis match.

Miki talks to Ginta in private about her feelings. Arimi tells a joke that makes Miki sad to think that she's no longer Ginta's closest female friend.

Miki is relieved to find that Ginta and Arimi's relationship had just been an act. Arimi shows up to tell Miki that she won't let her have Yuu.

Ginta reassures Miki that he'll wait for her to make up her mind. The entire school finds out about Meiko's relationship with her teacher.

Miki struggles with the fact that Meiko kept her relationship a secret from her. Yuu points out that everyone has something they keep to themselves.

Namura calls Meiko to say goodbye. Meiko tells her side of the story to Miki before leaving her to follow Namura back to his hometown.

Ginta and Miki come up with a plan to take Meiko on an outing to cheer her up. When they invite Yuu to come along, Arimi asks if she can join them.

Miki and Yuu's parents finalize their marriages. Yuu sticks by Miki's side to make sure she is feeling okay about the complicated situation.

Miwa and Yuu are rumored to be an item. Miki challenges Miwa at the school marathon after witnessing a strange exchange between the two boys.

Yuu has been too busy to talk to Miki during summer because of work. For some reason, Miwa shows up at their family vacation to see Yuu.

Yuu and Miwa invite Miki and Meiko out to see a movie. Miki stops worrying when she realizes that Yuu wants to help Miwa get together with Meiko.

Meiko invites her friends to vacation at her family's place in Izu. They meet Arimi and her posse at the beach and get together at night to hang out.

Miki becomes concerned about Yuu after learning his secret. Ginta gets showered with attention for his important upcoming tennis match.

Miki decides to tag along to support Yuu during the confrontation with his father. During the meeting, unexpected new information comes to light.