Manga Maou-sama to Kekkonshitai (Serialization)

One day, Haru, a young boy, is saved by the Demon Queen. They wanted to take him as a slave. The Queen protected him but wanted to turn the boy into her attendant. A few years pass when Haru grew up and became a handsome man, the Demon Queen asks him what she had to do. He agreed to marry her. An embracing story about the love of the beautiful Demon Queen and her servant.