Mika Ito attends the Academy as a swim team member, distinguished by her long green hair styled with a bunny ear-like headband, light blue eyes, and a slim frame, noted as one of the series' smallest characters. She alternates between her school uniform and swimsuit. Ito fiercely supports classmate Kaori Saeki's occult practices, relying on Saeki's tarot readings and reacting with volatile anger when black magic is doubted. Her devious nature emerges in her complicity during the locker room assault on swim teammate Miyuki Nonogusa by captain Shinobu Kobayashi and Mikimoto. After watching secretly with her boyfriend, Ito entered, taunted Nonogusa, enabled her boyfriend's rape of Nonogusa to take her virginity, changed into her swimsuit, kissed Mikimoto, and participated in ensuing group sex, suggesting a repeat. In "Bible Black: La Noche de Walpurgis," Ito confronted protagonist Taki Minase for dismissing occult rumors, prompting him to cast a spell forcing her to strip and masturbate publicly in class. Hospitalized with severe psychological trauma and suicidal thoughts, she later sought revenge: in one outcome, she fatally injected Minase with an aphrodisiac causing continuous ejaculation; in another, she stabbed him to death. Summoned by school nurse Reika Kitami, Ito visited the infirmary where Kitami kissed her, cast an arousal spell, and initiated intercourse despite Ito's resistance, revealing Kitami's large penis during the act. Branching paths show Minase allying with Kitami, who intercepted Ito's revenge attempt, subduing her magically and integrating her into their group via a simultaneous sexual encounter with both Minase and Kitami. Ito also joined an art club orgy with Saeki, Kurumi Imari, and Hiroko Takashiro. In "Bible Black: The Infection," Ito returned from absence to confront Minase in the infirmary. Depending on Minase admitting or denying his magic use, she either seduced him into intercourse—interrupted by his girlfriend Imari—or requested a "good memory" before performing oral sex on him, again disrupted by Imari. "Bible Black: Only" depicts Ito having sex with her boyfriend on a playground, mirroring an earlier rooftop encounter, and witnessing Kobayashi and Mikimoto's assault on Nonogusa. Here, she facilitated her boyfriend's participation in Nonogusa's rape before joining the group sexual activity.