Tachiaoi, 13, leads the Rat Squad in the Akane Class as an upperclassman, specializing in Body Jutsu combat to maximize her physical prowess. She has a petite frame, light skin, and bright brown eyes with round pupils. Her brown hair falls in bangs and five spiky strands—two longer at her forehead—typically tied in a shoulder-length ponytail with a light-red bow. She wears a light-red short-sleeved Uwagi jacket, a red Obi belt, short hand-warmers, and Sarashi shorts, always barefoot. Standing 165 cm tall, her birthday is August 19 under Leo. She enjoys accomplishment but dislikes sudden rain.

Prone to low self-esteem and pessimism, she often compares herself negatively to squad leaders like Tsubaki, whose charisma and leadership she admires. Insecure about her capabilities, she worries about meeting expectations. Her attempts to impress squad members Higuruma and Hagi frequently fail, deepening discouragement, yet their unwavering support renews her confidence and drive to lead effectively. Kind and caring, she treats them as friends, not subordinates.

Her leadership balances Higuruma’s optimism and Hagi’s negativity, though reconciling their views sometimes leaves her uncertain. She occasionally succeeds in her duties. Notably, Chapter 38 details her Double Knockout with Asagao during a confrontation, where both collided head-first.