Ichika Omori is a female physical education teacher who also serves as the homeroom teacher for Kanata Shinozaki's class. Her appearance is notably practical and low-maintenance; she typically wears a jersey, keeps her long brown hair tied up in a simple ponytail, and wears glasses, showing little interest in makeup or fashion trends. This style reflects her straightforward and no-nonsense attitude. Her personality is characterized by a blunt, honest, and somewhat tomboyish demeanor, often speaking in a direct, manly way. Known for her laid-back and easygoing nature, she is one of the more sensible and level-headed adults in the story, though she is far from perfect. Her primary personal quirks include a fondness for drinking and a strong aversion to troublesome situations or extra work, making her friendly but not particularly proactive unless absolutely necessary.

In her role as a teacher, Ichika employs a very hands-off philosophy, preferring to let her students manage their own affairs and problem-solve without her direct intervention. She attends class representative meetings but is often barely engaged, and her teaching style is defined by granting students a high degree of autonomy. Regarding her background, Ichika has been a long-time friend of her colleague Aoi Koshimizu since their own student days, and she frequently finds herself having to rein in Aoi's carefree and sometimes inappropriate behavior, acting as the sensible "straight man" in their duo. Outside of work, her romantic history includes an unspoken crush on a senior named Tanaka, who was a member of the track and field club during her school years. She never confessed her feelings and had resigned herself to the lost connection after graduation, only to be contacted by Tanaka years later and invited to a reunion, allowing them to reconnect.

Ichika's role in the story is primarily that of a sensible authority figure and a point of comedic contrast to the more eccentric characters, such as Aoi. Her key relationships are central to her character: her enduring friendship with Aoi defines much of her personal life, as she works to keep her friend in check, while her connection to her students, including Kanata, is defined by a deliberately distant, observational style. Her development appears in small moments, such as the quiet personal resolution of her lingering feelings for her old crush, Tanaka, when given a second chance to meet. As a physical education teacher, her notable abilities are implied to be athletic proficiency and competence in sports and other physical activities. She is affectionately known by the nickname "Icchan" to those around her.