Sekai-ichi Hatsukoi: The Case of Ritsu Onodera 5 (世界一初恋 〜小野寺律の場合5〜, Sekai-ichi Hatsukoi ~Onodera Ritsu no Baai 5~) is the fifth volume of the Sekai-ichi Hatsukoi manga series. The volume is released as The World's Greatest First Love: The Case of Ritsu Onodera 5 in English by SuBLime.
- The Case of Shouta Kisa No.4
- The Case of Ritsu Onodera No.8
- The Case of Ritsu Onodera No.9
- The Case of Shouta Kisa No.4.5
In "The Case of Shouta Kisa No.4," Shouta Kisa is still conflicted after seeing Kou Yukina with an unknown woman. Kisa's been avoiding him for several days and it's distracting him at work. Kisa finally takes one of Yukina's calls and tells him to see his girlfriend and essentially breaks up with him. An old hookup, Ichimura, later calls Kisa to see him and Kisa agrees. When Ichimura comes over to pick Kisa up, Yukina also arrives and chases Ichimura off. Yukina is able to explain to Kisa that the woman is a friend who he took to a movie in return for her teaching him to cook. Yukina and Kisa make up and have sex. Work is still hectic, and when Kisa comes home after another intense day, Yukina is waiting for him with a sleepover pack to stay at Kisa's for a week.
In "The Case of Ritsu Onodera No.8," it's the New Year's Party and Ritsu Onodera is still struggling with his arranged engagement. Ritsu's mother calls him at work, upset that he was not more attentive with An Kohinata the night before. She sets him up to see An again that evening despite his protests that he's working. That evening, Ritsu works at the New Year's Party, attending to all the authors, and after the party he's shocked to find An waiting for him. She confesses to him again, and he turns her down, clearly ending the engagement. Masamune Takano overhears the conversation and drives Ritsu home. He pushes into Ritsu's apartment and they have sex, and Ritsu thinks about An's comment that he might still be in love with the same person from ten years before.
In "The Case of Ritsu Onodera No.9," Takano gets sick. When he takes the day off, Ritsu brings his revised project proposal directly to Yokozawa, only to find that Yokozawa has also taken. After work, Ritsu stops by the store and picks up a bunch of medicine which he brings to Takano, but Yokozawa answers the door. They have another confrontation, where Yokozawa tells him to get lost and that Yokozawa is better for Takano. Flustered, Ritsu speaks just to be contrary, saying that Yokozawa should date Takano because it would be a relief for Ritsu. Just as he loudly declares that he hates Takano, Takano comes to the door, hearing everything.