Wakamatsu is a first-year high school student at Roman Academy, where he plays on the school’s basketball team. In middle school, he played under Umetarou Nozaki, who was the basketball team captain at the time. Although Wakamatsu admired Nozaki for his calm and reliable nature, he had no idea that Nozaki was also a shoujo manga artist.

After running into Nozaki in high school, Wakamatsu is recruited to help with his manga. Though he initially joins to assist with simple erasing tasks, he gradually becomes more involved in the manga production process, eventually working on screentones. His natural sensitivity and tendency to overthink situations often cause him distress, particularly due to the actions of Seo Yuzuki—unaware that she is the cause of both his stress and his serenity.

Wakamatsu is a tall teenage boy with short brown hair and soft, greenish-blue eyes. His expression is usually neutral or worried, giving him a somewhat innocent and passive appearance. He wears the standard Roman Academy school uniform, which consists of a white shirt, blue blazer, and tie.

When working on manga, he is often seen in casual clothes with sleeves rolled up, focusing intensely on his work. Despite being a basketball player, he lacks the confident posture or intimidating presence of other athletes, giving him a more timid aura.

Wakamatsu is a polite, reserved, and gentle person, but he’s also naïve, easily flustered, and frequently caught off guard by others particularly by Seo. He tries to avoid conflict and doesn’t handle stress well, often overanalyzing simple situations and reacting in extreme, irrational ways.

Despite his nervous nature, Wakamatsu is dedicated and hardworking, both as an athlete and a manga assistant. He values friendship and loyalty, especially toward Nozaki, whom he greatly respects. His reactions are often exaggerated for comedic effect, making him a consistent source of humor throughout the series.

One of Wakamatsu’s most notable quirks is his contradictory relationship with Seo Yuzuki. While he is constantly complaining about a certain “evil woman” who gives him insomnia and stress (Seo), he finds peace and comfort in the soothing singing of a mysterious “Lorelei” at choir practice completely unaware that both are the same person.

• Becoming a Manga Assistant
  After reconnecting with Nozaki in high school, Wakamatsu is recruited into his manga team, primarily tasked with erasing pencil marks. As he gains more experience, he begins to help with applying screentones, a skill he picks up quickly due to his natural patience and precision. Despite his lack of understanding about the romantic plots in the manga, he becomes a valuable—if emotionally fragile—member of Nozaki’s staff.

• The Seo Situation
  Much of Wakamatsu’s comedic storyline revolves around his tumultuous relationship with Seo Yuzuki. After being paired with her during basketball practice, Wakamatsu develops intense stress due to her aggressive and thoughtless behavior, labeling her as “the evil woman.” Ironically, he also finds solace in the beautiful singing voice of a girl he refers to as “Lorelei,” unaware that it’s Seo herself during choir practice. To deal with his insomnia caused by Seo, he starts listening to recordings of Lorelei’s voice, which calms him down immediately. This ongoing situation becomes one of the series’ major running gags, as neither he nor Seo makes the connection between her two identities.

• Inspiration for Waka
  Nozaki uses Wakamatsu as the model for Waka, the male lead in Let’s Fall in Love. Waka’s innocent and easily flustered reactions are directly based on Wakamatsu’s behavior, especially his romantic confusion. Much of Nozaki’s humor in writing comes from observing Wakamatsu’s responses to Seo’s antics, essentially making Wakamatsu the muse for his own suffering in fiction.