Trinity Seven S01 E06 Dark Mage and Big Event

Liese, the last Trinity Seven, appears in the Eternal Library bearing a demon lord seal, making her a demon lord candidate, as well. She tries to entice Arata to join the evil mage side to help save Hijiri, and kisses Arata while he's unsure what to do. Arata has his magic stolen from him, and Liese decides to attack the school.