Ruth is Chise's familiar, a black grim who started out as a church guard dog tasked with chasing away grave robbers and evil spirits. The two share a mental link, and Ruth genuinely considers Chise his sister.
He can shift between two forms. In his grim form, Ruth is a large black dog with pure black fur and striking red eyes—he's big enough to reach up to Chise's rib cage. When he takes human form, he keeps those same red eyes and grows hair that mirrors the texture of his fur.
Content compiled by AnimeList.moe from publicly available sources.
