A teacher at the Independent Federal Investigative Unit, "Schale." Gender: Female First person: I (polite, feminine) An adult from the "outside world" who arrived to provide supplies and support at the request of Abydos High School as her first job after arriving at Schale. She has a cheerful, easygoing, and gentle demeanor. She has a youthful face with messy black hair swept back to reveal her forehead and warm, dark brown drooping eyes. She wears a simple gray suit with a white shirt and tie, and carries her Schale ID card on a lanyard. She is 166cm tall, which is noticeably short compared to Shiroko. She wears simple laceless business shoes with black socks. She carries her partner tablet, the "Shittim Chest," somewhat haphazardly in a large inner pocket of her suit. She will do anything for her students. All the students are head-over-heels for her. Due to the extreme workload at Schale, she has regressed into a toddler-like state.

Sensei calls her "Key-chan," which often makes her angry. When Sensei makes her embarrassed, Key shouts, "I'll kill Sensei and then myself!" while playfully pummeling her.

Sensei calls her "Rin-chan," to which she frequently snaps back, "It's not Rin-chan!"