《在魔王城说晚安》改编自熊之股键次创作的同名漫画作品，故事发生在一个人类与魔族共存的时代。某一天，魔王突然抓走了人类公主，并威胁说：只有向魔族交出世界的支配权才能够拯救公主。人类受到了激怒，勇者为救回公主而踏上了旅途。而被囚禁在魔王城中的公主，原本应该在绝望中每天以泪洗面等待救援，但结果却是闲得发慌，为了获得更安稳的睡眠而把魔王城闹得鸡飞狗跳

"Say Goodnight at Demon Castle" is a Japanese adaptation of the manga of the same name created by Kenji Kumanogus animated film. The film is composed of outstanding voice actors such as Inori Minase, Matsuoka Matsuoka, Ishikawa Kaito and Kobayashi Osohiro. Directed by Mitsue Yamazaki and Junie Noro, it will be released in 2020. The film shows the coexistence of humans and demons in a fantasy setting, and incorporates elements of warmth and comedy, bringing the audience a fantasy journey full of laughter and emotion.

The story takes place in an era when humans and demons coexist. One day, the demon king suddenly kidnapped the human princess and offered to surrender the control of the world as a condition for saving the princess. Human beings were angered, and the brave embarked on a dangerous journey to save the princess. However, at the same time, the princess imprisoned in the Demon King's City is living a comfortable life. She has nothing to do, and even made a series of disturbances and jokes in pursuit of a better sleep.

The film reveals the relationship and growth of the characters in a humorous way. The princess was supposed to be waiting for rescue in despair, but she broke the inherent role setting in her own way. She showed an optimistic and positive attitude towards life, which not only filled the Demon King City with laughter, but also brought a touch of warm emotion to the film. At the same time, the brave man also gradually changed while getting along with the princess. He learned to understand and tolerate, and discovered true courage and responsibility.

The humorous element in the film is one of its highlights. From the hilarious scenes of the princess romping around the castle to the comic dialogue between the characters, viewers will have a good time laughing and laughing. These humorous moments not only add a relaxed atmosphere to the film, but also make it easier for the audience to empathize with the characters.