Tamaki Saimon is a twelfth-grade student with long, straight brown hair typically secured in a waist-length or longer ponytail by a ribbon hair tie. Her garnet-colored eyes are tareme-shaped, and she possesses a slim, pale physique, standing 162 cm tall with measurements of 84-59-80 cm and a C cup bust. Her birthday is March 3.

She favors clothing such as school uniforms, miniskirts, thigh-high stockings, sweaters, tank tops, jackets, scarves, aprons, and garments featuring ribbons or detached sleeves. Bikinis occasionally appear in her wardrobe.

Tamaki exhibits a carefree, friendly, and deredere personality marked by approachability and optimism. She maintains an active social life as a classmate and part-time worker, often engaging in cooking activities. Her background includes a longstanding childhood friendship with Rouma, which evolved to include a physical relationship without formal romantic commitment. She terminates this arrangement due to Rouma's repeated negligence regarding contraception during their encounters.

Concurrently, Tamaki is in a committed relationship with an unnamed medical student from a wealthy background, a dynamic that exists alongside her unresolved history with Rouma. Following the physical separation, interpersonal tension and distance define her interactions with Rouma, particularly during shared club activities. Peers like Yuuri notice this strain and attempt to mediate reconciliation between them.