Episode 1 begins with a story about the main character Koshi Hirako and her hometown. On her way to school, she is observed by several deer. Koshi, a second-year student and student council president at Tokyo Metropolitan Hinominami High School, is introduced as the perfect girl, though she hides a criminal past.

On her way, Koshi saves a girl from falling. Shortly after, she discovers another girl hanging from a utility pole. The girl with antlers is unharmed but stuck. After some back and forth, Koshi frees her and heads to school.

There, the teacher introduces a new classmate, who turns out to be the antlered girl Shikanoko Noko (Nokotan). Nokotan’s dramatic entrance, where she smashes the door with her antlers, shocks everyone. She sits next to Koshi and immediately calls her "criminal," exposing Koshi’s secret past.

Koshi tries to maintain her image as a model student while Nokotan’s wild antics threaten to reveal her secret. During class, Nokotan gifts Koshi deer-shaped cookies and her own antlers as thanks for saving her in the past. Koshi refuses the antlers, but Nokotan insists, showing her willingness to give up her unique identity for Koshi.

Their dynamic is complicated by Nokotan’s mischievous nature and Koshi’s need to hide her past. Nokotan’s teasing continues until Koshi takes her to the student council room to ask her to keep quiet about her criminal history. Nokotan agrees, but not without further playful taunting.

Later, Koshi finds Nokotan injured in a school shed. She helps her and learns that Nokotan is cleaning the shed to start a deer club. Their teacher, Ms. Ukoi, arrives and informs Koshi that she will be the president of the Deer Club, which takes care of deer. Nokotan becomes the "deer" of the club.

The episode ends with Nokotan giving Koshi a brush to groom her antlers and hair, while another girl watches from a distance. The narrator concludes by announcing that the adventures of the Deer Club have now begun.