"Ayakashi Triangle" is a supernatural action-comedy manga series written and illustrated by Kentaro Yabuki. The story centers on Matsuri Kazamaki, a young exorcist who protects humanity from malevolent spirits known as ayakashi. Matsuri is skilled in combat and possesses a deep understanding of the spiritual world, often working alongside his childhood friend, Suzu Kanade, who has a unique ability to sense ayakashi. Their partnership is tested when a powerful ayakashi named Shirogane targets Suzu due to her rare spiritual energy.

During a confrontation with Shirogane, Matsuri is transformed into a girl by a curse. This gender transformation becomes a central element of the narrative, as Matsuri must navigate his new identity while continuing to protect Suzu and fight ayakashi. The curse also complicates Matsuri's relationship with Suzu, who remains unaware of his true identity for a significant portion of the story. The dynamic between the characters is further enriched by their shared history and the emotional tension arising from Matsuri's altered state.

The series blends action, humor, and supernatural elements, with Matsuri frequently engaging in battles against various ayakashi while adapting to his new circumstances. The narrative explores themes of identity, loyalty, and the bonds of friendship, as Matsuri strives to break the curse and return to his original form. Supporting characters, such as other exorcists and ayakashi, add depth to the story, contributing to both the comedic and dramatic moments.

As the plot progresses, Matsuri and Suzu uncover deeper mysteries surrounding the ayakashi and the origins of the curse. Their journey involves uncovering ancient secrets, confronting powerful adversaries, and strengthening their resolve to protect each other. The series maintains a balance between lighthearted comedy and intense action, with the evolving relationship between Matsuri and Suzu serving as a key emotional anchor.