Tengoku ni Ochiro!

Overview

"I love Leo more than anyone in the world." Yuri and Leo are a lovey-dovey couple in the demon world. Frustrated by their laziness, Yuri's father, the Great Demon King, gives them a task: "Go to the human world and make as many humans fall to the dark side as possible." While Yuri handles the training efficiently to become a fully-fledged demon, Leo, who is kind and struggles with expressing his emotions, has a hard time progressing in his tasks... What will become of their grand romance that spans both the human and demon worlds!? (Source: Libre, translated) Note: Includes one extra chapter.

Source: AniList