Minami goes to her groom, Asakura's house on their wedding day because he hasn't arrived at the wedding venue yet. She meets Sena, a pianist who is Asakura's former roommate before he moved out without Minami knowing. Desperately, Minami even offers marriage to Sena.
Shinji shows up at Minami's place with Rumi and mistakes Sena as his brother-in-law. Surprisingly, Shinji plays the piano really well. Meanwhile, Sena explains to Ryoko about who Minami is and asks Ryoko to go to a recital with him. Afterward, they go to a restaurant for dinner and accidentally meet Minami who is quite drunk already.
Minami has some trouble at work and is later fired, but she quickly adjusts herself. She wants to apologize for what happened at the restaurant, so she offers to bring Sena and Ryoko to Shinji's club. It turns out that Ryoko and Shinji have met before. They hit it off at the club right away which breaks Sena's heart. After Minami and Sena return home, they learn about some surprising news.
Shinji doesn't go home to Rumi after taking Ryoko home. Everyone is worried that they might sleep together. Sena is especially down because of it. Ryoko meets Minami at a restaurant to talk about what happened and Sena also goes to the same place with Professor Sasaki.
After Sena confesses his feelings for Ryoko, she accepts it. They start dating but still discover some incompatibilities. Meanwhile, Sugisaki asks Minami to go to a concert with her. At the concert, she meets Ryoko and Shinji.
Ryoko breaks up with Sena, saying she likes someone else. Sena gets depressed, but luckily, Minami is there for him. As for Minami, after failing another interview, with the help of Sugisaki, she finally finds a job as his assistant. Ryoko, on the other hand, encouraged by Momoko, decides to confess her feelings to Shinji. Sena and Minami kiss for the first time.
Minami is distracted because she keeps thinking about her kiss with Sena and she loses an important envelope from work. She keeps searching for it but to no avail. Meanwhile, Professor Sasaki invites Sena to join a music competition. If he wins, he'll become a pianist in Boston. Shinji lives at Sena's house after he is kicked out by Rumi.
Minami decides to move out of Sena's place. Meanwhile, Sena finally joins the piano competition. However, he then finds out that Minami is leaving. As for Minami, she learns that Sugisaki has divorced and has a child which concerns her a lot.
Sena originally plans to join the piano competition, but he suddenly decides that it's time to stop playing the piano instead. He quits his job in the music classroom and finds a regular job. Once Minami finds out, she is determined not to let Sena give up.
Sena enters the competition after talking to Minami. On the other hand, Sugisaki proposes to Minami, but she doesn't reply. When Sena finds out about the proposal, he is devastated. However, sadness helps him play the piano better as he passes the competition.
After performing well in the preliminary competition, Sena is offered to sign with a music label. However, if he agrees to sign, he can't join the competition anymore. The people around him aren't optimistic that he'll win the competition and advise him to withdraw. Meanwhile, Minami and Sena sleep together, but they are unsure about the status of their relationship and what the future holds for both of them.