Shou Marui captains Aota Academy's girls' volleyball team, excelling as their primary attacker in the left-front position and recognized as the team's top player. Her strong leadership motivates teammates through intense competitive drive and a willingness to push beyond her physical limits during matches, sometimes resulting in excessive physical strain. As leader, she maintains a responsible and approachable demeanor while privately grappling with the role's pressures. Shou combines modesty, approachability, athleticism, and a spirited attitude.

Physically, she possesses dark red hair, blue eyes, stands 176 cm tall, and has measurements of 81-57-82. Her blood type is A.

Romantically, Shou develops strong feelings for the team's coach, Oh Motoura, soon after his arrival. Her persistent attraction remains a reserved crush, contrasting with the overt advances of teammate Kozue Nekoda, and Shou refrains from openly expressing her deep affection. Kumi Marui is identified as her sister and fellow volleyball team member, though their specific relationship dynamics receive limited elaboration.