"My Oni Girl" centers around the life of Hikari, a high school student who leads an ordinary life until a chance encounter with Yuki, a mysterious girl with oni heritage. Yuki, possessing supernatural abilities tied to her oni lineage, becomes intertwined with Hikari’s world after saving him from a dangerous situation. As their paths cross, Hikari learns that Yuki is on a quest to find her missing father, a powerful oni who disappeared under mysterious circumstances. The two form an unlikely partnership, with Hikari offering his support despite his initial reluctance and fear of the supernatural.

The narrative unfolds as Hikari and Yuki navigate a series of challenges, including encounters with other supernatural beings and the uncovering of secrets about Yuki’s family. The story explores themes of identity, belonging, and the tension between the human and supernatural worlds. Yuki’s struggle to reconcile her oni heritage with her desire for a normal life becomes a central focus, while Hikari’s growing courage and loyalty are tested as he becomes more deeply involved in her quest.

Supporting characters include Hikari’s classmates, who provide moments of levity and grounding in the human world, as well as other oni and supernatural entities who either aid or hinder the protagonists. The plot is driven by a mix of action, mystery, and emotional moments, as the duo uncovers clues about Yuki’s father and confronts the forces that threaten both their worlds. The series balances its fantastical elements with relatable human experiences, creating a narrative that is both engaging and thought-provoking.