Kyou kara Maou! revolves around Yuri Shibuya, your average Japanese teenager. One day, Yuri sees a classmate being harassed by bullies. Thanks to this intervention, his friend is able to escape, but unfortunately Yuri becomes the new target of the bullies in the process and gets his head shoved into a toilet. But instead of water, the toilet contains a swirling portal that sucks him into another world, largely resembling medieval Europe. There, he is told that he will become the next Demon King due to his black hair and black eyes, traits only possessed by the demon's royal lineage. Yuri's arrival is met with some skepticism by some of the demons, who view him as unworthy to be their king. However, after Yuri wins a duel by utilizing his magical powers, the demons slowly begin to acknowledge him as their monarch. Yuri must now learn what it takes be a true Demon King, as he tries to keep the peace between demons and humans in this strange new realm.

Life has returned to some form of normalcy after the end of the series, and so His Majesty Yuuri Shibuya travels to oversee how things are going. While doing so, he runs into the king of Small Shimeron--Sararegi. But it seems there may be something more to him than the friendly king he presents himself as. Yuuri go back to Shimaron to relax and meet some friends, when the king of Little Shimaron suddenly joins the group and wants the Maou to come to his country. The Original king sends a message to Yuuri's brother and his friend that Yuuri is in trouble. (Source: ANN)

At the end of season 2. Yuuri defeats Shinou, but since Shinou had been defeated, Yuuri and Murata could no longer go to the Shin Makoku. However, because Yuuri had fought and defeated him, his powers had surpassed that of Shinou's, resulting in him being able to rely on his own power to return to Shin Makoku. After the ceremony at the age of 16, Yuuri slowly begins to discover that much has happened while he was away. The ten officials of the noble family have decided to make Wolfram the next Maou, but now that Yuuri has returned and taken back his role as Maou, complications arise when one noble disagrees with Yuuri returning to the throne. In addition, an ancient secret society that threatens the peace of both humans and Mazoku has risen, and a fight for the throne that now leaves the nobles wondering who is the legitimate Maou.

On a school yachting trip, fifteen children of various ages are mysteriously transported to another world where dinosaurs still roam. While attempting to return home, they encounter talking dinosaurs, revolutionaries, pirates, a princess and primitive scientists. These unlikely allies help them escape from soldiers, bandits, vicious dinosaurs, and fanatical priests. Aggression between the two oldest boys leads to a split in ranks, and a sneaky double cross plot. Unlikely romances bloom in this tense atmosphere, and the group learns that each has strengths that can help them get home, if they work together. Loosely based on the book Deux ans De Vacances, by Jules Verne from 1888. (Source: ANN)