"Onipan!" is a 12-episode anime series that centers around three middle school girls—Tsutsuji, Himawari, and Tsukishiro—who are descendants of oni, mythical Japanese demons. Despite their heritage, they are determined to change the negative perception of oni in their town by performing good deeds and helping others. The girls form a group called "Onipan" to carry out their mission, blending their supernatural abilities with everyday school life.

The narrative explores their efforts to balance their dual identities as both ordinary students and oni descendants. Each episode typically features a self-contained story where the girls encounter various challenges, often involving their classmates or townspeople. These challenges range from mundane school activities to more fantastical situations that require their oni powers. The series emphasizes themes of friendship, community, and self-acceptance, as the girls learn to embrace their unique heritage while striving to be seen as kind and helpful rather than fearsome.

Tsutsuji, the leader of the group, is energetic and determined, often taking charge of their missions. Himawari, the most reserved of the trio, provides a thoughtful and cautious perspective, while Tsukishiro, the youngest, brings a playful and mischievous energy to the group. Together, they navigate the complexities of adolescence, using their oni abilities in creative ways to solve problems and win over the hearts of those around them. The series combines lighthearted humor with moments of heartfelt sincerity, creating a balance that appeals to a wide audience.