Miki's parents come home from their vacation to announce that they are getting a divorce. But what is more shocking is that they have switched partners with another couple! And to top things off, this other couple has a handsome son, Yuu, who Miki begins to develop feelings for. To make things more disturbing, everyone moves into one house. What will everyone think about Miki's family lifestyle?
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 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.
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.
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.
Yuu and Miki enjoy an ordinary morning together after their conversation at the beach. Miki hopes that her feelings for Yuu will last forever.
Miki starts to feel insecure when Yuu accepts his mother's job offer to appear in a commercial with a beautiful young model named Suzu.
Yuu gets very busy with his job and commercial shoots. Despite barely having time to see Miki, Yuu makes sure to keep her in his thoughts.
Miki can't bring herself to tell Yuu that she lost the medallion. Her co-worker Kei, on the other hand, doesn't tell Miki that he has it.
Yuu's reluctance to talk about the commercial makes Miki's mind wander to dark places. Kei keeps missing the chance to tell Miki about the medallion.
Miki's mind fills with doubt about Yuu's tutoring arrangement with Suzu. Miki follows Kei into a live music venue after work.
After seeing Miki in Kei's arms, Suzu jumps to the conclusion that she must be cheating on Yuu. Miki gets glared at by Suzu at the school festival.
Miki suffers in silence as the four parents discuss the topic of Suzu kissing Yuu at the concert. Suzu asks Kei about his relationship with Miki.
Miki wonders if Yuu is cold to her because of what happened at work. Yuu unwittingly shows up to a Halloween party at Suzu's house.
Miki mistakenly thinks that Yuu wanted to keep the party a secret from her. All goes according to Suzu's plan as Yuu and Miki begin to drift apart.
Yuu leaves Miki behind to go travel by himself. Kei gives the medallion back to Miki, but he won't forgive Yuu for making her sad.
Yuu's old friend Anju starts calling him every day. Miki pretends not to mind in order not to come across as being jealous again.
Ginta and Arimi grow closer together after the embarrassing incident. Miki learns from Yuu that Anju helped him deal with his problems in the past.
After revealing her feelings, Anju begs Miki if she can borrow Yuu for a day. Miki is unable to object despite being uncomfortable with the idea.
Anju contemplates getting a potentially fatal surgery. Miki's uncertainty grows when Yuu reveals he didn't know what to say after Anju's confession.
Kei performs his original piano music for Miki on Christmas Eve. Yuu rushes to Anju's side after being notified that she has collapsed.
Miki gets a toy ring from Yuu when they pay a New Year's visit to the shrine with their friends. Suzu's father tells Yuu to consider studying abroad.
After making an assumption that Yuu is planning to go on a trip with Miki, Suzu tries to ruin their travel plans by convincing everyone to go skiing.
Miki realizes that she hasn't given much thought about her future career path. Meiko believes her dream of becoming a writer is unrealistic.
Meiko receives a lot of media attention for her story about heartbreak after Miwa enters a prestigious writing contest on her behalf.
Despite being told not to get her hopes up, Meiko heads to Hiroshima to see Namura. There, she tells him she wants to be by his side and keep writing.
Meiko returns to her hotel with Miki after getting rejected again. Frustrated at his inability to help, Miwa tries to punch the truth out of Namura.
Miki makes last-minute Valentine's Day treats. When she goes to deliver Yuu's gift, she sees him getting hit on by a female college student.
Meiko gets engaged to be married to Namura after graduating high school. Miwa and Meiko meet up at the library to straighten things out.
The parents arrange to host a foreign exchange student at their place. Miki mistakes the new arrival for Yuu and runs straight into his arms.
Miki barely has time to talk to Yuu as Michael settles in to his new surroundings. Yuu finds it hard to tell Miki about his plan to study abroad.
Miki feels betrayed about Yuu's decision to go to America. Yuu says that his feelings for her will never change, but Miki finds that hard to believe.
Miki and Yuu plan an overnight trip before he departs for New York. Michael shows up in Hakone under the impression that they're on a group trip.
Yuu quickly makes friends at his dorm. The blond and beautiful Jinny offers to show Yuu around after falling in love with him at first sight.
Jinny claims that Yuu and Miki are not in a real relationship if they haven't gone beyond the kissing stage. Kei wins a music contest back in Japan.
Miki and Meiko begin to feel the effects of being in a long distance relationship. Michael asserts that he will steal Miki's heart while Yuu is away.
Meiko's parents ignore their daughter's pleas for them to meet Namura. Namura's calm attitude feeds Meiko's insecurity as he encourages her to write.
Miki and her friends attend Kei's piano competition. Although it puts him at a disadvantage, Kei chooses to play the piece he wrote for Miki.
Miki agonizes over being told that Yuu has a girlfriend in America. Yuu runs into Anju and invites her to spend a weekend with him and his friends.
Miki calls Yuu's dorm and discovers that he went away for the weekend with Jinny and his other friends. Michael and Kei get into a fight in public.
Miki decides to go see Yuu. While she convinces their parents that she is visiting New York to help Meiko, she fails to tell Yuu about her trip.
Miki considers going back to Tokyo without ever seeing Yuu. When Will calls Anju to ask her out, Yuu finds out that Miki is in town.
Michael confesses his feelings to Miki after her breakup with Yuu. Kei sees through Miki's facade as she tries to put on a brave face.
Will explodes with anger when Jinny reveals what she has done. When Yuu calls home to talk to Miki, Michael tells him that she is on a date with Kei.
A package arrives from Yuu. Miki talks to Anju about the sad truth. Kei arrives in New York for a competition and tells Yuu about his intentions.
Miki decides to move on, but she keeps seeing things that remind her of Yuu. Michael and Kei take Miki to a theme park to help her make up her mind.
Miki decides to start going out with Kei. Unable to accept Kei as a suitable choice, Ginta cancels a date with Arimi in order to look after Miki.
Arimi decides to break up with Ginta. After hearing Arimi's side of the story, Miki tells her that she and Ginta should express their feelings more.
Yuu makes up his mind to go to Japan after talking with a friend. Anju finds herself falling back in love with Yuu as he expresses his kindness.
Yuu heads back to Japan for the first time since the breakup. Miki feels uncertain as she goes to the airport to see him with her family.
Miki goes camping with her friends and family. Despite being playful with Kei, Miki can't help but feel sad about her current situation with Yuu.
Miki and Yuu discuss getting each other presents to make up for the birthdays they missed while they were apart. Yuu finds his father's old photos.
Yuu's words shatter Miki's world into a thousand pieces. In order to prevent the family from falling apart, Yuu chooses to keep the truth to himself.
Judging from Miwa's serious tone, Meiko deduces that Yuu must be hiding something. Miki stores away all of the things she ever received from Yuu.
Meiko gives Miki the courage to go see Yuu in New York. When Miki confronts him with her feelings, Yuu is left with no choice but to tell his secret.
Yuu's American friends approve of his relationship with Miki after seeing their determination. Miki and Yuu's parents straighten out the facts.
