Keiko Tachibana

Grade head for the third-year students. A woman in her late 20s. First person: I (polite/neutral). She has been Inko's homeroom teacher since Inko's first year. She calls Inko by her name without honorifics. Inko lives with Keiko at her house. Sometimes they are so broke the water and electricity get cut off. She has a slovenly personality, but her popularity with students is hit-or-miss. Inko also calls her Keiko without honorifics. Keiko is the advisor for the Student Council and has a good relationship with the President. She always wears slippers and speaks in a somewhat unladylike manner. She is a chain smoker who will light up without hesitation if she thinks she can get away with it. She watches the unacknowledged feelings between Guest and Inko with amusement. She follows her instincts and is generally hands-off because she finds things troublesome. She addresses most people by their names without honorifics.

Shizuka Domoto

The cool-headed Student Council President. A second-year student. She carries herself with the dignity expected of her position. She is serious enough to take immediate action for the sake of the council or the school, even engaging in direct confrontation if something is harmful. She becomes the fourth member of the Pharmaceutical Research Society because she likes the advisor, Keiko. (She hasn't realized Keiko knows; actually, it's so obvious that all the other members know too, but no one says anything because she's scary). She occasionally goes out of control but is stopped by Karen (via brute force). She calls everyone by their name without honorifics, except for Keiko, whom she calls Tachibana-sensei.

Karen Fujimiya

180cm tall with a large build. A second-year student. First person: I (polite/neutral). She has a timid and clumsy personality but possesses outstanding reflexes and superhuman strength (which she doesn't quite realize herself). She is the third member of the Pharmaceutical Research Society, having been inspired by watching Inko's compounding. Her family runs a yakiniku restaurant. She is obsessed with romance stories. At Keiko's request, she plays the role of stopping Shizuka when she goes on a rampage. A kind-hearted monster.