Reika Aoshima, a student at East Oizumi Academy, serves as a key member and co-leader of the school's Cosplay Club alongside president Gorou Yorozuyo. She actively drives recruitment and retention efforts crucial for the club's stability. Her serious, occasionally stern demeanor can appear unfriendly as she directs members toward cosplay goals, visibly expressing frustration when faced with disorganization or wavering focus. Despite this outward strictness, Reika possesses a deeply emotional core. Intense passion, desire, or embarrassment readily triggers strong blushing and flustered reactions, sometimes overwhelming her. This vulnerability fuels her determined, though indirect, efforts to orchestrate a romantic connection between club member Chako Hasegawa and college student Kosuke Tamiya. She harbors significant shyness about her own appearance, specifically hiding her need for corrective eyewear from everyone except Gorou.

Within her cosplay activities, Reika demonstrates pragmatic audience engagement. She strategically leverages her physical attractiveness in costume as a deliberate tactic to draw fan attention during competitions and club promotions, overcoming her general shyness in service of the club's objectives. Her dedication remains consistent. An unresolved narrative element involves a mysterious blue-haired woman whose presence at significant events (including a cosplay battle and a graveside visit) visibly surprises another character, Sachiko; Reika shares no direct interaction or confirmed connection with this figure. Information regarding her background, family, or life beyond the club setting is unavailable. Her character development across all official media, including OVAs and the "Extra Identification" short, focuses exclusively on her role within the Cosplay Club. Details concerning her appearance or involvement in spin-offs, movies, or expanded universe content beyond the original OVAs are absent.