The series focuses on a 5-year-old Heian-era prince named Ojarumaru Sakanoue who accidentally time-warps to modern Japan and has adventures there while dodging a trio of young oni who try to get back a scepter that he stole from Great King Enma.

[8] Around 1,000 years ago in Fairy World (妖精界 Yōsei-kai) in the Heian era,[d] a young prince from a noble family named Ojarumaru Sakanoue is bored of his life of privilege.

While making many new friends and rivals, as well as dodging the Oni Child Trio's efforts to retrieve the scepter, Ojarumaru has many adventures in Moonlight Town (月光町 Gekkō-chō) and encounters new things he has never seen before in his time period.

Later episodes tend to center around other characters, including Princess Okame, Ojarumaru's young fiancé who desperately tries to win over his heart; Okorinbō and Nikorinbō, two anthropomorphic komainu who try numerous get-rich-quick methods in a bid to get their shinto shrine out of poverty; Ken, a freeter who keeps changing jobs; Kazuma's classmates, big eater Kintarō Sakata, beauty-obsessed Komachi Ono, and the judgmental but well-intentioned Kentarō Iwashimizu; Icchoku Honda, Kazuma's energetic homeroom teacher; the Hoshino Family, three aliens from another planet who want to invade Earth and have a strange aversion to Ojarumaru; and Sachiyo Usui, an eccentric manga artist who is notorious for her creepy, highly detailed drawings.

These include Momotarō,[10][11][12] Cinderella,[13] Ikkyū-san,[14] Journey to the West,[15] Columbo,[16] Peter Pan,[17] The Boy Who Cried Wolf,[18] Attack on Titan[19] and James Bond.

[26] A manga adaptation of the anime series, written and illustrated by Tatsuma Ejiri, was serialized in Shueisha's Saikyo Jump magazine from January 2012 to September 2014.