Isekai Maou to Shoukan Shoujo no Dorei Majutsu

Synopsis

Diablo dreams of his childhood where many of his so-called friends would use him and then abandon him. While alone with Shera, he finds he can easily craft potions. Outside, Keera plays a flute that hypnotizes Shera into leaving with her brother. Depressed about being abandoned again, Diablo mopes, but Rem and Alicia eventually deduce that Shera was hypnotized and the group plots a rescue. Keera chains Shera up in his tent and interrogates her on her relationship with Diablo, not believing her when she says Diablo did not touch her. Keera unleashes a fabric-eating slime creature to destroy her clothes and prepares to rape her, but the group arrives in time, having already defeated his guards. Keera uses the flute to hypnotize Shera again and make her lie that she wants to stay with her brother, but Diablo uses his authority as the master of her collar to make her tell the truth, and she says she wants to stay with Diablo and Rem. Infuriated, Keera summons a monster called the Force Hydra.

(Source: Wikipedia)