Sekai-Ichi Hatsukoi: Onodera Ritsu no Baai (世界一初恋 〜小野寺律の場合〜?, lit. "The World's Greatest First Love: Onodera Ritsu's Affair") is a Japanese boys-love manga series written and illustrated by Shungiku Nakamura. In 2011, the manga was adapted into an anime television series under the title Sekai-ichi Hatsukoi. Produced by Studio DEEN under the direction of Chiaki Kon, the anime series began its broadcast run on April 9, 2011. An original animation DVD was bundled with the fifth and sixth volumes of the manga series, released in March and September 2011.

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 might have done it. Despite this obvious evidence, he openly denies this taking place.