Kuro Ten no Maou ~Mamono no Kotoba ga Wakaru Ore, Shiitagerareta Mamono-tachi no Kyuuseishu to Nari Saikyou Kokka wo Tsukuriageru~

Ellen Ark, a man who can understand the language of monsters, used his ability to work at the Tamer Guild. However, he was persecuted by people who found him unsettling, partly because he shared the black hair of the former Demon Lord, a historical enemy of humans, and partly because he could communicate with monsters.

Eventually, the Guild Master, who viewed Ellen as a heretic, unjustly expelled him.

Just when he had lost everything and faced the brink of death, the bonds he shared with the monsters awakened a new power within Ellen—!