Hiroko Takashiro, a respected high school art teacher, mentors students Taki Minase and Kurumi Imari in the art club, her approachable nature cementing her popularity within the academic community. Twelve years prior, she spearheaded a student group intent on founding a witchcraft club. Denied official recognition, they uncovered a black magic tome, conducting clandestine experiments that culminated in casting a spell on student council member Junko—an act triggering Junko’s public humiliation and ostracization. This incident solidified the covert coven’s formation under Hiroko’s leadership.

The group later crossed paths with Reika Kitami, a transfer student whose initially innocent demeanor belied her eventual transformation. Their escalating rituals, fueled by the forbidden text, reached a critical juncture with an attempt to harness dark forces—a rite doomed by Kitami’s non-virginal status. The catastrophic failure unleashed supernatural havoc, binding Kitami to a malevolent pact while Hiroko alone emerged unscathed, etching the tragedy into the school’s legacy.

Years later, Hiroko discerns Kitami’s resurgence as she manipulates students through revived occult practices. Compelled to act, Hiroko confronts Minase, cautioning against Kitami’s schemes and positioning herself as a vigilant voice against recurring darkness. Her survival of the past disaster fuels her resolve, though the occult’s lingering influence stifles her efforts.

Spanning eras, Hiroko’s narrative shifts from orchestrator of arcane pursuits to a tormented guardian, navigating the repercussions of her youth while striving to shield others from the shadows she once invoked.