Ursula

Ursula is Yuri's guardian for all her life whose sole duty to protect her from demons and outsiders.she wears a cape and a weird cap on her head also wears glasses and has silver hair .she is master of magical powers , knows all type of magic including wind,fire,elemental type of magic.she is lil bit of hotheaded as well,when Ein fell into the dungeon he met Yuri and Ursula there .thanks to Ursula's training he became weakest to strongest in a very short time.