Mihoshi Mizutani serves as the cheerful homeroom teacher for Sasami Kawai's class at Umi no Hoshi Elementary. Her background features a distinct mixed ethnic heritage: her grandfather was American, her grandmother Thai, her father Japanese, and her mother identified as "Mixed." This diversity sets her apart within the continuity. Her original character design incorporates an Okayama accent that emerges when she becomes angry.

Mihoshi exhibits a laid-back, encouraging teaching style, frequently organizing extracurricular activities like beach trips and classroom celebrations for achievements. She emphasizes positive reinforcement, congratulating high performers like Misao Amano and Kenji without criticizing others. This approach contrasts with the stricter methods of fellow teacher Kiyone Amayuri, whose class engages in friendly rivalries with Mihoshi's students, such as dodgeball tournaments. Despite this perceived rivalry, Mihoshi considers Kiyone a close friend, their relationship dating back to junior high school.

Despite her characteristic airheaded personality, Mihoshi demonstrates unexpected professional competence. She effectively teaches elementary-level mathematics and holds a college education, a detail established in the OVA continuity where she attended college while Kiyone did not. Her ability to manage her classroom and engage students underscores this capability.

In alternate continuities like *Sasami: Magical Girls Club*, Mihoshi retains her teaching role but appears only in limited cameos without interacting with main characters or her usual associates Kiyone or Noike. A canceled sequel, *Sasami:14*, would have featured Mihoshi and Kiyone as junior high school teachers. The *Pretty Sammy* novel universe provides additional context, explicitly stating her mixed ancestry originates from "many different countries." The "Magical night 2" audio play presents a divergent interpretation, portraying her as originating from another planet, unlike other continuities where she is human.