Sekai Ichi Hatsukoi: The World's Greatest First Love

Onodera leaves the office to visit the bookstore and thinks about how it has felt whenever Takano has touched him, but he dismisses these thoughts. At the bookstore, he runs into Yokozawa, and as they leave together, Yokozawa demands that Onodera move to a new home. Onodera argues that it his none of his business and teases Yokozawa that maybe he and Takano were dating. Yokozawa confirms this suspicion and Onodera realizes that Yokozawa doesn’t like him because he is protecting Takano. Back at the office, Onodera overhears a conversation between two women, one of whom saw Takano and Yokozawa together the night before. Takano invites Onodera to dinner, and though Onodera declines, Takano makes the plan anyway. Onodera tries to avoid having dinner with Takano, but Takano catches him and they go to dinner at Takano’s apartment. At dinner, Onodera becomes intoxicated and drunkenly confesses that Takano’s behavior has an emotional effect on him. The next morning, Onodera awakens to find himself naked in Takano’s bed, unable to remember the events of the previous night, but pain in his hips and back leads him to realize that he and Takano had had sex. Despite this obvious evidence, he openly denies this taking place.

Onodera reflects upon how he imagined Christmas would be when he and Takano were together 10 years ago. Onodera runs a manuscript over to the printers and upon arriving back at the office, he receives an email from Takano telling him he can go home. As the elevator door opens, he sees Takano and Yokozawa talking and when the leave together, Yokozawa asks what Onodera’s plans are for the 24th, which happens to be Takano’s birthday. Yokozawa then implies to Onodera that he and Takano are still together, and he warns Onodera again to stay away from Takano. Onodera wishes Takano a happy birthday and as they part, Takano requests Onodera’s company on a drive for his birthday gift. On the drive, Onodera reflects on his feelings toward Takano, and Takano reveals the true nature of his relationship with Yokozawa and reminds Onodera that he has loved him for 10 years. They kiss, and Onodera admits to himself that he cannot resist Takano.

As Yoshino struggles to meet a looming deadline, he wishes his assistant Yanase could help but doesn't ask, knowing Hatori despises him. Yanase appears of his own accord and helps finish the project but Yoshino collapses from overwork. On awakening, Hatori tells him he was rushed to the hospital and has slept for two days. After Yoshino recuperates, Yanase reveals he has romantic feelings for him. Just then, Hatori walks in and immediately exits. After not hearing from Hatori for a week, Yoshino arranges a meeting between them. When a gloomy Hatori says he expects ...

Yoshino is conflicted between his fondness for Hatori and his friendship with Yanase. Hatori makes a movie date with Yoshino but cancels at the last minute due to work. That same day, Yoshino becomes upset when he spots Hatori with an old high school girlfriend. While brooding over the incident, Hatori calls Yoshino, who hangs up on him. Yanase invites Yoshino to his house, where they recall Hatori's former girlfriend from high school and Yanase implies that Hatori is cheating on Yoshino. Hatori phones and Yanase tells him he intends to make Yoshino his boyfriend. ...

Onodera receives a call at work from An, a girl his parents arranged to be his fiancée, who wants to meet at his apartment that night to give him a New Year's present. Takano overhears the conversation and ask Onodera if she is his girlfriend, which he denies. Later, as they approach their apartment building they see An waiting for Onodera. Takano again asks if she is his girlfriend and An is taken aback when Onodera answers 'No'. After An departs, Onodera is concerned that Takano misunderstands his relationship with the girl and contrives a way into his apartment. ...

Marukawa Publishing executive Isaka Ryuichiro is in love with his assistant Asahina Kaoru. He recalls when they met as children, through the time when Isaka hoped to become a writer. One night Isaka suddenly kisses Asahina and his affections are rejected. Asahina quits Marukawa to become assistant to Isaka's father. When Isaka confronts Asahina about this, the latter confesses his love for Isaka, explaining he had earlier rejected him because he thought Isaka already knew of his love and was making sport of him. Shaken by the confession, Isaka wonders how they could ...

While preparing for the company's New Year's party, Onodera gets a call from his mother, who pesters him about his engagement to An and asks him to escort her from a wedding that coincidentally is taking place in the same hotel as the company event. At the party, Onodera encounters Yokozawa, who accuses him of slacking at work but Takano defends him. Onodera is surprised to find An waiting for him since he had told his mother he couldn't see her. An reiterates her love for him but Onodera tells her he can't love her the way she wants him to. An asks if he loves ...

Kisa has the perfect boyfriend in Yukina but is riddled with doubts about their relationship. He is concerned his heavy work schedule prevents them from being together often and interprets Yukina's understanding of the situation as a sign of indifference. Kisa's fears are heightened when a colleague tells him she's getting married because a job can't provide the same stability as a relationship. When Kisa finally makes a date with Yukina, he's delayed because of a work commitment. When he calls to explain, Yukina suggests they put the date off and an angry Kisa hangs ...

Believing Yukina has cheated on him, Kisa becomes distracted at work and won't respond to Yukina's messages. Accidentally answering one of Yukina's calls, Kisa tells him their relationship is over. That night, Kisa reflects on Yukina and realizes he knows little about him as their time together was mostly spent having sex. Kisa receives a call from an old boyfriend and agrees to hook up with him since he's no longer seeing anyone. The man arrives and just as he and Kisa start to kiss, Yukina appears, slaps Kisa's face and tells the other man to leave. Inside Kisa's ...

Onodera enters the office elevator with Yokozawa and Takano, who he is coming down with a cold. Onodera is jealous when Yokozawa touches Takano to take his temperature. Takano corners Onodera in the lunch room and reminds him of what he told fiancée at the New Year's party. Onodera tells him he only told her he loves someone else due to circumstances. The next morning, Onodera hears that Takano is out of the office due to illness and he wonders if anyone is taking care of him. That night he brings medicine for Takano but Yokozawa answers the door and the two get into ...

Takano and Onodera share a moment in the rain and talk about their time in school. A few startling truths are revealed that may change their opinion about each other.

Takano remembers how he fell in love with Ritsu and his problems with his family. This is the season finale.