Ousuke Kiryu possesses short black hair swept to the right and dark brown eyes, marked by a distinguishing mole beneath his left eye. Childhood heart issues restricted his physical activities, leading to peer neglect and social isolation. This fostered heightened observational skills, granting him acute perception of people and social dynamics. Despite this adaptability, early exclusion ingrained persistent trust issues and emotional detachment.

He adopted a pragmatic approach to relationships, consciously acting as a "moodmaker" within groups to prevent abandonment. He demonstrates inclusivity regardless of gender. While this strategy cultivates surface-level friendships, it masks a deep fear of being left alone. His past includes a specific friendship initiated by a classmate named Asano, complicated by Ousuke's guarded nature which hindered his ability to embrace vulnerability even with kind companions.

As a member of Meiryo High's koto club, Ousuke enhances group cohesion. His playing style mirrors his history: technical precision and emotional control produce a sound often perceived as "cold" or detached. This contrasts with warmer performances, showcasing his skill in synchronizing and elevating the ensemble while revealing his emotional barriers. The piece "Hyakkafu" performed by his team, embodying fleeting moments and solitude, reflects his worldview.

His preferences include a fondness for handmade crafts, especially those gifted by girls, and a strong aversion to hospital food stemming from past medical experiences.