Yamada, a high school girl, is determined to lose her virginity but sets an unconventional goal: to have casual sex with 100 partners. Despite her bold aspirations, she lacks confidence in her appearance and struggles with her inexperience. To achieve her objective, she decides to start with someone she perceives as safe and unthreatening, choosing her classmate Kosuda, a shy and average boy who seems unlikely to reject her. However, Yamada’s lack of experience and her tendency to overthink every interaction complicate her plans, leading to a series of humorous and awkward situations.

As Yamada and Kosuda navigate their budding relationship, their interactions reveal deeper layers of their personalities. Yamada, despite her bravado, is insecure and inexperienced, often masking her vulnerability with exaggerated confidence. Kosuda, initially overwhelmed by Yamada’s forwardness, gradually develops genuine feelings for her, though he struggles to express them. Their dynamic evolves from a one-sided pursuit into a mutual, albeit clumsy, exploration of intimacy and emotional connection.

The series explores themes of adolescence, self-discovery, and the complexities of relationships, blending comedy with moments of sincerity. Supporting characters, such as Yamada’s best friend Miharu and Kosuda’s friend Kanejou, add depth to the narrative, providing contrasting perspectives on love and sexuality. The story balances humor with occasional introspection, highlighting the characters’ growth as they confront their insecurities and misconceptions about relationships.

Throughout the series, Yamada’s initial goal of casual encounters becomes secondary as her feelings for Kosuda deepen, challenging her original intentions. The narrative emphasizes the importance of emotional intimacy over physicality, portraying the characters’ journey as they navigate the awkwardness and vulnerability of first love. The series concludes with an open-ended resolution, leaving the characters’ futures ambiguous but suggesting continued growth and connection.