Reiko Tamai operates as an administrator and observer in the games’ hierarchy, directly supervising Group K and its leader, Juuzou Kadokura. Her striking appearance features long blonde hair, golden eyes, and a bold fashion sense: an unbuttoned black jacket layered over a casually open dress shirt, paired with a mini skirt and vibrant red shoes. Energetic and impulsive, she channels her fervor most intensely in romantic pursuits, prone to forming swift, passionate attachments rooted in love-at-first-sight convictions. Even when recognizing flaws in her snap judgments, she clings stubbornly to initial impressions, fueling a cycle of whirlwind romances that flare brightly before collapsing abruptly. Within the narrative, she debuts during the clash between Group K and Group C, boldly betting on her group’s triumph due to their strategic prodigy and superior numbers, wagering with fellow administrator Tsukino that the game would end within three days. Later, in the sixth game’s second half, "Friend’s Murder Game," she joins hunter Maria Mizuse in active pursuit, deploying immobilizing black spheres to escalate the stakes for players.