Manabu Sotoin presides as founder and president of Yubiwa Academy's detective organization, established after his older brother Odoru Sotoin relinquished leadership upon entering high school, deeming such activities unsuitable. Officially titled "Manabu the Aesthete," he governs the club through beauty as its core principle.

He possesses bright blue hair, pale skin, and prominently sharp frontal teeth when smiling. His attire features a modified elementary uniform: a sleeveless green vest layered over a white shirt with black cuffs, vertically striped black-and-white trousers, and a galaxy-patterned tie. For covert missions, he adopts a female disguise with a long twintail wig and Yubiwa Academy’s girls' uniform.

Manabu displays a cheerfully carefree demeanor, often speaking expansively regardless of context. Despite his youth, he commands older members with sharp deductive skills and unwavering confidence. He routinely declares, "Unfortunately, I am not learned. What I have is just aestheticism," asserting beauty—not academic knowledge—as his decision-making compass. He dismisses shallow interpretations of the club’s name, clarifying their pursuit centers on inner spirit over mere physical appearance. His leadership binds the group’s varied personalities.

Nicknamed "Kogoro" for his fifth-grade status, this alias also honors Kogoro Akechi from Edogawa Ranpo’s Boy Detective Club series, which inspired their own foundation. The club follows four cardinal rules, the second—"Be a boy"—embodying Manabu’s conviction to preserve childlike wonder and imagination in investigations.

Within the collaborative novel *Mazemonogatari*, intersecting with the *Monogatari* series, Manabu guides protagonist Mayumi Dojima to observe celestial phenomena at North White Snake Shrine, showcasing his role in cases demanding extraordinary sight. His past includes an injury from tumbling down stairs during a confrontation with Kodaki Kawaike, a recruit he rejected by stating the club was "no place for a maiden in love."