While in Chinese the term maou means something so cute and innocent as “cat”, the Japanese version is a tad more dramatic, meaning “demon king”.
In Japanese mythology we come across the term “Mazoku”, which refer to evil or dark supernatural creatures.
The “maou” is the ultimate evil, supernatural creature – he is the leader of all the “mazoku”. He is the kind of the demons, or a super powerful monster.
In Japanese, the term is usually spelled Maō, hence “maou” is the anglicisation of the term. “Ma-” is a reference to the “mazoku”, while the letter “ō” in Japanese means king or ruler.
Apart from evidence that the term goes far back in Japanese language, no exact time can be traced.
Japanese bible translations refers to the Devil as a “maou”, and the concept can be seen in Japanese polytheism as well.
Oda Nobunaga, known as the “great unifier” of Japan, once referred to himself as “maou” in a letter. He signed it as “the demon king(maou) of the sixth sky”.
In Japanese fiction, particularly manga and anime, the good and evil principle makes room for great “maou’s”, dark lords who are in never ending fights with the hero protagonist.