TV-Series
Description
Hazuki Oikawa is a first-year student at an agricultural university, making her a freshman alongside the protagonist, Tadayasu Sawaki. She joins the group of students who become attached to Professor Itsuki's laboratory after an incident involving her compulsive cleaning habits.

The most defining aspect of her personality is her status as a compulsive neat freak, or germophobe. She is intensely preoccupied with cleanliness and has a deep-seated fear of dirt and bacteria, which leads her to constantly carry disinfectant tissues and antibacterial sprays. This fear is a primary driver of her actions and creates significant conflict within the story. Her personality has also been described as having tsundere traits, which refers to a character who is initially cold or hostile before becoming warmer and more affectionate.

Hazuki's role in the story is primarily defined by her ignorance of the microbial world that the protagonist Sawaki can see. Because of her germophobia, Sawaki decides to keep his unique ability to see and communicate with microbes a secret from her. This lack of knowledge leads to her causing major problems for the other characters. In one notable incident, she accidentally destroys a batch of caterpillar fungus that two sophomore students, Kaoru Misato and Takuma Kawahama, were illegally cultivating in their dorm room by spraying the area with her antibacterial solution. Her actions often place her at odds with the other students who are more comfortable with the microbes involved in their agricultural and fermentation studies.

In terms of key relationships, Hazuki interacts closely with the core group of students in Professor Itsuki's lab, including Sawaki, Kei Yuki, Aoi Muto, Misato, and Kawahama. Her relationships are complicated by her conflicting personal statements and actions. While she has proclaimed a preference for older men, her interactions with her peers sometimes contradict this. For instance, she has been physically intimate with another male student, Aoi Muto, and has behaved in a forward manner with other male characters. She also has a noted interaction with Haruka Hasegawa, a postgraduate assistant in the lab; Hazuki's main reaction to being kissed by Hasegawa was simply annoyance.

Hazuki undergoes a significant and ironic development by the end of the second season. Despite her intense fear and dislike of germs, Sawaki discovers that she has become a powerful microbe-magnet. The sheer number of microorganisms orbiting around her becomes so immense that Sawaki can no longer see her body through the dense cloud of microbes. This development stands in stark contrast to her initial character traits and serves as a major twist on her neat-freak nature. There are suggestions that her character may be perceived by some viewers as being out of place in the series due to her lack of knowledge about microbes, and her primary narrative function is to demonstrate how Sawaki interacts with people who are unaware of his special power.