Maria Inomata is a high school student at Morinomiya Academy and holds the position of the highest achieving student in the advanced class. She is known for her strict adherence to school rules and a low tolerance for students who do not take their studies seriously, which often distances her from her peers. Her harsh and rule‑oriented exterior initially makes her appear unapproachable, but she is revealed to be a person who struggles with expressing her emotions, a trait that can intimidate young children when she first encounters them.

Her role in the story begins when she warns Ryuuichi Kashima about the noise the daycare children make in the school corridor. Despite her initial disapproval, she later visits the daycare room, indicating a gradual opening up to the babysitting club. Over time, she joins the cooking club in high school and occasionally brings homemade snacks and bread to the children at the daycare, showing a caring side that contrasts with her strict public persona.

Maria develops a crush on Ryuuichi, which further softens her demeanor. She is not naturally gifted at interacting with children; her inability to easily convey warmth causes some of the youngest children to feel uneasy around her. Nevertheless, her dedication to academics and her eventual involvement in club activities demonstrate her growth from a purely studious, isolated individual to someone who begins to connect with others through shared efforts. Her notable abilities include exceptional academic performance, placing her at the top of the advanced class, and a developing talent for cooking that she uses to contribute to the daycare community.