"Kimetsu Gakuen Valentine-hen" is a comedic spin-off of the popular series "Demon Slayer: Kimetsu no Yaiba," reimagining its characters in a modern high school setting. The story unfolds during Valentine's Day, focusing on the humorous and lighthearted interactions between the students as they navigate the traditions of giving and receiving chocolates. The narrative centers on Tanjiro Kamado, a kind-hearted and diligent student, who becomes the object of affection for several classmates. His sister, Nezuko, also plays a key role, often accompanying him and adding to the comedic dynamics.

The plot explores the various characters' attempts to express their feelings through Valentine's chocolates. Zenitsu Agatsuma, known for his dramatic and often exaggerated reactions, becomes overly anxious about receiving chocolates, particularly from his crush. Inosuke Hashibira, with his brash and competitive personality, misunderstands the concept of Valentine's Day, leading to chaotic and humorous situations. Meanwhile, the stoic and aloof Giyu Tomioka and the strict yet caring Shinobu Kocho add their own unique quirks to the mix, creating a series of comedic vignettes.

The series also highlights the interactions between the Hashira, the elite upperclassmen, as they engage in playful rivalries and misunderstandings. Mitsuri Kanroji, known for her cheerful and affectionate nature, becomes a central figure in the Valentine's Day festivities, while characters like Obanai Iguro and Sanemi Shinazugawa provide contrasting personalities that further enrich the comedic tone. The narrative maintains a light-hearted and episodic structure, with each character's perspective on Valentine's Day contributing to the overall humor and charm of the series. The setting and character dynamics remain faithful to the original series' personalities, but the modern high school backdrop allows for a fresh and entertaining reinterpretation of their relationships.