Kenji Yanagimoto is a student at Ousai Private Academy and serves as the director of the movie club. He is introduced as a friend and classmate of the protagonist Takatoshi Tsuda and Mutsumi Mitsuba during their first year, later becoming classmates with Suzu Hagimura and Chiri Nakazato in the second year. In terms of appearance, Kenji has short, spiky grey-black hair and wears a pair of half-rimmed glasses that typically conceal his eyes, standing at roughly the same height as Takatoshi.

Kenji's background and initial motivations are notably different from Takatoshi's. While Takatoshi chose Ousai for its proximity to his home, Kenji is implied to be one of the harem-seekers mentioned early in the series, referring to boys who deliberately enrolled at the academy because it had recently transitioned from an all-girls school to a co-ed institution, resulting in a heavily skewed boy-girl ratio. He was confident that this imbalance would naturally lead to romantic attention, at least to the extent of receiving chocolates on Valentine's Day. However, as Takatoshi pointed out, simply being one of the few boys did not automatically guarantee interest from the female students. This initial hope is repeatedly disappointed, as his attempts to prepare for Valentine's Day, such as gelling his hair, fail to yield results, though he eventually does receive chocolate casually from Chiri Nakazato.

Kenji's personality is characterized by a brief flash of jealousy toward Takatoshi for being chosen as the sole male member of the student council, surrounded by its beautiful female members. He once expressed a wish to take Takatoshi's place, but immediately backtracked when the offer was made, as he understood the job would be difficult and wanted no part of it, an attitude that irritated Takatoshi. Aside from this initial harem-seeking objective, Kenji settles into the role of a relatively normal teenager, especially when compared to the more eccentric characters that populate the series. He embodies typical teenage interests and behaviors, often engaging in mundane conversations with Takatoshi about video games or their lack of preparation for tests. Takatoshi genuinely appreciates these interactions, as such normal discussions are impossible with the brilliantly unconventional student council members. While Kenji often serves as the straight man in comedic routines, he is also one of the few characters to deliver a sharp retort to Takatoshi, specifically calling out his denseness when several female students fought over being his tennis doubles partner.

Kenji's most significant relationship is with Takatoshi Tsuda, whom he is likely best friends with outside of the student council. He also maintains a friendly rapport with classmates like Mutsumi Mitsuba, who is noted for being able to get along with everyone, and Kenji is well aware of her abilities to the point of panicking if she acts out of character. In the Japanese fandom, Kenji is often paired with Chiri Nakazato. Kenji's role in the story is that of a recurring supporting character, providing a grounded, male perspective from outside the student council. His development is subtle, as his initial ambitions for romance gradually fade into the background of his routine school life. Despite being one of the few male characters, he makes relatively few appearances and has even fewer speaking roles compared to the main cast. His position as the director of the movie club is noted, but his activities in that capacity are rarely documented or shown.