Kuro

Kuro is a Cat Sidhe and the familiar of Rin Okumura. He previously served as the familiar of the priest Shiro Fujimoto until Shiro's death at Satan's hands, after which he bonded with Rin.

Long before joining the Okumura household, Kuro was worshipped as a guardian deity by local silkworm farmers. When silk cultivation declined and his shrine was demolished, the abandoned spirit lashed out at the humans responsible. Shiro was sent to subdue him, and instead calmed Kuro with an offering of catnip wine and an invitation to become his familiar, giving him a new purpose as a guardian of True Cross Academy.

Playful and affectionate, Kuro spends most of his time by Rin's side, often napping on his back, though he can turn fierce when someone he cares about is threatened. He struggles with loneliness and openly grieved Shiro's death, but has since grown close to Rin and Yukio's classmates as well.