グールが世界を救ったことを私だけが知っている, Only I Know the Ghoul Saved the World, Ghoul ga Sekai o Sukutta Koto o Watashi dake ga Shitteiru

I am not a brave man. I am a monster who eats monsters. In the world of chaos, where vicious demons are rampant, and the holy city is the last stronghold of the dying human race, there is a "demon" who has inherited the title of "hero".... Alice, a new adventurer, is attacked by a horde of dogmen on her first exploration of the labyrinth. The person who saves her life is Leon, the third generation of "Salvation" heroes, who has the body of a demon but the mind of a human. I am nothing but a filthy ghoul who just keeps on killing demons. For some reason, she adores him, and Leon volunteers to become her apprentice.