Rjú no šódžo (Wiene) (S03E01)

Bell Cranel's rapid growth, his victory in the war games, and the increase in his family members, among other things, has lead to a continuing rise in the visibility of the Hestia Familia in the labyrinth town, Orario. With advances in the dungeon going well, they have arrived on the Nineteenth Floor - the labyrinth of the Great Tree. In the height of battle, Bell is forced to act solo and rescue a girl being attacked by monsters... But this trembling, crying girl is, herself, a monster. (Crunchyroll)