Koi no Hate Made, Yoru Yami no Oni Sarawarete

Princess Lunafilia, who was neglected and mistreated since childhood due to a leg ailment, is forcefully married off to the tyrant of an enemy nation.

Though she felt repulsion, Lunafilia suppressed her desire to choose her own path, believing that for someone like her to want freedom was selfish, and the day of her departure arrived. However, before she could reach the enemy nation, she was abducted by a monstrous being named Cain, who is feared by the people as the "King of the Night's Darkness."

This is a doting fantasy romance depicting a demon king whose love is too heavy and a lonely princess.