Obsessed with their rather ordinary classmate Ken Kirio, high school students Aimi Miyoshi and Nami Sometani form a peculiar friendship. Every time the girls hang out, they talk about Kirio and fantasize about interacting with the boy they usually just observe from afar. Aimi and Nami are mostly satisfied with the status quo, but they occasionally cannot help but be jealous of those who get to be near their crush—though this still rarely leads them to approach him directly.

Nestled away on the rooftop of Tenikai General Hospital is the unconventional Department of Investigative Pathology headed by the eccentric Dr. Takao Ameku. The tiny department, consisting of Takao and her sole resident Yuu Kotori Takanashi, treats complex cases that most other departments within the hospital cannot resolve on their own. The mystery-obsessed Takao always tries to insert herself into cases that capture her fancy—much to the dismay of her colleagues and the police. Even if her meddling creates more problems for the hospital and those around her, none can deny the brilliance that the young department head exhibits as she weaves a diagnosis together. No matter the specialty, no case is impossible for Takao and a somewhat reluctant Takanashi to solve.