Oto Edogawa has to keep her family's bankruptcy a secret in order to stay at Eitoku Academy. Her worst nightmare comes true when the C5's leader Haruto Kaguragi finds out she has a job. She has some leverage from learning his secret at the time. To keep her quiet, Haruto tries to impress her which fails miserably.

After saving her from a coworker, Haruto has Oto eat pancakes with him as repayment. He later takes her to Tsukasa Domyoji's house, where Oto reveals she is engaged to Tenma Hase. Haruto feels inferior next to Tenma, who is student president of Eitoku's rival Momonozono Academy.

Jealous of Oto, Airi Maya reveals that she is a "commoner". Oto decides to drop out of Eitoku, which would thus end her engagement. Tenma pays her donation and saves her in time from a crowd of bullies. At the hospital, he confesses his feelings to her. Haruto and Oto later become friends.

Airi pretends to befriend to Oto only to lock her and Tenma in a storeroom. Haruto then severs his friendship with her. Oto later becomes concerned about Airi when she goes missing. In the process of helping her, Oto earns Airi's respect and friendship.

Megumi Nishidome enters Haruto's life after a chance meeting. Oto starts to feel mixed-up when she sees them together. She later asks Tenma to date her officially, to which he readily agrees. Meanwhile, Megumi decides to pursue a romantic relationship with Haruto.

Oto and Tenma encounter Haruto and Megumi, while on a date at an amusement park. Now a double date, it becomes increasingly awkward. Tenma later alludes to being jealous of Haruto. Oto realizes she has to settle things with Haruto, which she does. He is devastated by rejection.

Oto and Haruto become friends again following an attack on Eitoku. He later plans Megumi's birthday party, while Oto prepares for a dinner with Tenma's parents. She is late when a second attack happens at Megumi's party. Haruto helps convince Tenma's parents about her strong feelings for their son.

Oto learns that Jin Konoe is behind all of the attacks, but Tenma does not believer her. Haruto sees her upset and Megumi tells him to cheer her up thus ending their date. Later that night, he hugs her which Tenma sees and confronts him about. Haruto's father suggests a contest between the two.

Despite realizing her feelings for Haruto, Oto decides to support Tenma in the contest. The C5 enlist Sojiro Nishikado to train Haruto, who is hopeless at martial arts. Megumi, meanwhile, struggles with whether to support Haruto or not since their relationship will be over if he wins.

After easily winning the first round, Tenma's confidence is shaken when he learns the truth about Konoe. Megumi breaks up with Haruto after he wins the second round. He wins the whole competition. Afterwards, Tenma ends his engagement to Oto and encourages her to follow her feelings. She then races to meet Haruto.