Hiroko Takashiro (高城 寛子 Takashiro Hiroko) is a major character in the original Bible Black game and its sequel Bible Black: The Infection. She also plays a major role in the anime adaptions Bible Black: La Noche de Walpurgis, its prequel Bible Black: Origins and sequel Bible Black: New Testament. Additionally, she is also featured in two scenes of Bible Black: Only.

During her student years, Takashiro starts her own witchcraft club with her classmates. The club gains considerable influence around the Academy after the girls find the Bible Black spell book. However, Takashiro's attempt to summon an actual demon to gain his power backfires, and her club's leadership is usurped by student council president Nami Kozono, forever changing Takashiro's opinion about occult magic.

Twelve years later, Takashiro becomes an art teacher and faculty advisor to the art club at the same school she attended herself. She is confronted by her past when school nurse and witch Reika Kitami reveals her true identity. Along with her art student Taki Minase, Takashiro tries to stop the evil woman from exchanging souls with student Kurumi Imari.