No es que no pueda casarme. No me caso.

Miyabi Tachibana, 39, is beautiful, intelligent, and successful. At her high school reunion, her former classmates gather around her to bask in her brilliance, but their looks of awe turn into pity when they learn she is still single. Miyabi insists she is single by choice, but the experience leaves her shaken. That night, Miyabi goes to an expensive restaurant with her unmarried friends, and they have a good time poking fun at men. The restaurant chef and owner, Seiji Tokura, listens in disdainful silence but eventually snaps when they unwittingly disrespect his dishes. He berates the women and calls Miyabi a textbook example of a woman who will never be able to marry. Deeply offended, Miyabi seizes her chance to prove Tokura wrong when she runs into Sakurai, her old high school crush.

Miyabi decides to ask Tokura for advice on love and romance, and he instructs her to get a temp boyfriend to build up her confidence. Miyabi's work schedule prevents her from finding the time to do so, but a suggestion from Rika, a nurse at Miyabi's clinic, leads to the both of them going to a climbing gym to meet eligible men. There, Miyabi meets Ishida, an average-looking man who is interested in her. Miyabi is thrilled, but her hopes are dashed when she realizes he only approached her to get a referral letter for his sick mother. To get Miyabi back on her feet again, Tokura teaches her how to make herself attractive to men. She follows his advice to great success at a matchmaking party, but things go awry when a doctor takes an interest in her.

Miyabi succeeds in getting a temp boyfriend, Ishida, who tells her he wishes to marry her if they prove to be a good match. Miyabi feels guilty about using Ishida for practice but decides to follow Tokura's advice in hopes of eventually getting together with Sakurai. On their first date, Ishida tells Miyabi everyone calls him "Mr. Average" because he is thoroughly average and does not stand out in any way. Miyabi is disappointed, but Rika tells her that average men are hard to come by and persuades her not to write him off just yet. Miyabi goes on a dinner date with Ishida but finds it difficult to overlook his shortcomings. When Tokura overhears Miyabi complaining about Ishida to her friends, he seizes the opportunity to give her another lecture on love.

Eri, Sakurai's ex-girlfriend from Indonesia, has come to Japan to get back together with him. Shaken by this sudden turn of events, Miyabi waylays Tokura on his morning jog to ask him for advice. Tokura analyzes the situation and concludes that Eri's assertive personality makes her a formidable rival. Miyabi is dismayed to hear that it is only a matter of time before Sakurai and Eri are back together, but Tokura tells her not to give up so easily. He instructs Miyabi to attend as many group dates as possible to gain experience, and she immediately arranges one with the nurses from her clinic. Unfortunately, she has been out of practice for too long, and everything she says on the group date falls flat. Miyabi's confidence is shaken, but Tokura is not done with his lessons.

A heartbroken Miyabi has too much to drink and wakes up the next morning to find Ryotaro in her bed. Miyabi regrets her impulsive actions, but Ryotaro does not seem to mind. Tokura quickly catches on to their relationship and instructs Miyabi to give in to her desires. He wants Miyabi, who is still hung up over Sakurai, to regain her confidence by dating Ryotaro. Miyabi enjoys her relaxing dates with Ryotaro but is dismayed when she realizes he does not think of her as his girlfriend. She turns to Tokura for advice, and he teaches her how to get Ryotaro to commit to a serious relationship. Meanwhile, Sakurai aspires to be a good father like Tokura when Tokura's wife and daughter show up at the restaurant, but Tokura's marriage is not what it appears to be.

Burning with curiosity, Miyabi invites herself into Tokura's penthouse after discovering they live in the same building. There, she learns that his wife Chinami has left him, taking their daughter with her. Miyabi is able to tell, just by looking around Tokura's penthouse, why his marriage failed. She relishes the opportunity to turn the tables on him, but he tells her to get out. Tokura's pride prevents him from asking Miyabi for help, but he eventually gives in and invites her to his restaurant. With the help of Yuri, Miyabi's ex-classmate, the two women teach Tokura to look at things from his estranged wife's point of view. Why did Chinami leave Tokura, and can he win her back? As Tokura tries to fix his broken marriage, Miyabi begins to suspect Eri is hiding a secret.