Saneyasu Adachi is a high school student and koto club member at Tokise High, distinguished by his medium-length black hair—often tied back—and dark eyes. His height shifts from 175cm to 177cm, reflecting subtle growth. In winter, he wears a white shirt paired with a red-and-orange striped tie, checkered brown pants, and brown shoes; summer swaps this for a light blue polo, its top button casually undone.

Raised alongside an older sister with a fiery temper and a mischievous younger sister, Saneyasu occupies a cherished role in their dynamic. Both sisters hold him in high regard, habitually measuring others against his example. His culinary preferences lean toward ramen, chao fan, and fizzy drinks, with no noted aversions.

Once a delinquent, he channels his reformed spirit into the koto club, joining peers on a similar path. Their collective dedication transforms the group from the brink of disbandment to national-stage contenders, emphasizing rigorous practice and shared ambition. While his individual backstory remains sparingly documented, Saneyasu’s presence anchors the club’s pursuit of musical mastery, underscoring a narrative of unity and disciplined resurgence.