This is the first chapter of the Kaifuku Jutsushi no Yarinaoshi manga series.
Summary[]
The hero Freia takes a young boy named Keyaru to become a hero and save the world. However, upon learning that he was a healer, and that using his ability hurt in in return, Freia tortures him in a cell while sadistically pouring him a painkiller drug. Enraged, Keyaru promises to get revenge.
Later in Freia's room, the captain suddenly assaults her and reveals himself to be a disguised Keyaru, who had somehow escaped captivity. When Freia attempts to rationalize her behavior, Keyaru completely disregards it and prepares to rape her.