Karin Mibu serves as a melee instructor at the academy and is also a member of the Tempelritter, an organization of knights. Her weapon of choice is a pair of katanas named Kotetsu and Kikuichimonji, showcasing her skill in dual-wielding swordsmanship.

In terms of personality, Karin appears fearless and composed, even when facing Angels in battle. However, this outward bravery conceals a notable vulnerability: she has a well-documented fear of ghosts. Beyond combat, she has softer and more personal interests, including a love for nesagi, small rabbit-like creatures, and a fondness for composing haiku poetry. Another defining trait is her very poor sense of direction.

Karin's primary motivation and role in the story are deeply tied to her past relationship with a character named Theresa. The two were originally good friends, and Karin would frequently visit an orphanage for war orphans that Theresa looked after. Their friendship was shattered when Karin came to believe that Theresa had led those same orphans to be slaughtered by the Tempelritter. Consequently, the former friends became bitter enemies, and this betrayal serves as a central driver for Karin's actions throughout the narrative. Her key relationships are defined by this tragic turning point, shifting from a close bond with Theresa to one of conflict and distrust. Information on her development beyond this backstory is limited.