High school student
Osamu Kurihara (栗原 オサム, Kurihara Osamu) is the boyfriend of Nanako Yamazaki.
Osamu is an average teenager with an afro and a thin build. He is mostly seen in his school uniform.
Osamu is a kind-hearted, emotional and excitable person who is loyal to his friends but dense when it comes to matters of the heart. Nonetheless, he is hard working and treasures those close to him particularly Nanako Yamazaki (Osamu's girlfriend). He is somewhat of a coward when it comes to violence, but is willing to put himself in danger to further his relationship with Nanako.
Osamu develops a crush on Nanako after she glared at him for complimenting her legs; saying she was the one for her reaction. He and Nanako had exchanged contact information and would sometimes go on dates in private, Kurihara even holding her hand. Nanako develops feelings for him as well, but isn't quite convinced he really likes her. On Christmas, Kurihara climbs the karaoke bar's Christmas Tree and grabs the legendary star and confesses his feelings to her. She accepts and the two start dating. They had a faster progress than Takeo Gouda and Rinko Yamato, as they kissed on the night they got together and started referring to each other by first name and without honorifics very early in their relationship; they are additionally very lovey-dovey and often do their own thing separate from the group.
- Osamu's surname Kurihara means "chestnut plain".
- Osamu becomes Nanako Yamazaki's boyfriend on Christmas in volume 5.
- Osamu originally referred to Nanako as "Nanako-chan," but once they begin dating, he just calls her "Nanako".