Ojarumaru Sakanoue, a mischievous 5-year-old prince from the Heian-era Fairy World’s noble Sakanoue clan, embodies whimsy and aristocratic nonchalance. Preferring leisure over labor, he lounges on his ever-present three-piece set—a portable pedestal, folding screen, and armrest—or hitches rides on his best friend Kazuma Tamura’s back or backpack to evade exertion. His theft of Great King Enma’s reality-warping scepter, which enables judgment of the dead, catapults him through the Moon Hole into modern Moonlight Town, sparking relentless pursuit by Enma’s oni offspring: the Kooni Trio. Aobei, Kisuke, and Akane relentlessly chase the scepter, but Ojarumaru thwarts them with cunning evasion and playful mockery, dubbing them "Kooni mera" or nicknaming Kisuke "Hiyoko" for his chick-like fluff.

Archaic speech peppered with "de ojaru" and "tetamo" underscores his noble roots, while self-references as "Maro" and addressing others as "Sochi" highlight his regal quirks. Mispronounced modern terms draw corrections from Denbo, his dutiful firefly attendant, or Kazuma. Surprises trigger his trademark "Oja!" while encounters with Princess Okame, his tenacious Heian-era fiancée, elicit an exasperated "Ojazozo!"

His fourth-dimensional eboshi hat harbors oddities collected across adventures, and his obsession with Kazuma’s mother Ai’s pudding sparks comical clashes when others dare claim his treats. Averse to water, he dodges baths and aquatic settings with princely defiance.

Though bonded like brothers, Ojarumaru and Kazuma occasionally feud over trifles, while Denbo juggles caregiving with the prince’s manipulative whims. The Kooni Trio’s antics amuse more than intimidate him, showcasing his blend of indifference and cleverness. His episodic escapades weave through encounters with aliens, talking animals, and folklore-inspired figures, yet the series’ structure preserves his ageless, unchanging spirit—a spoiled yet endearing relic of aristocracy navigating time-displaced mischief.