Ikusabe Wataru is an ordinary, cheerful elementary school student with an average disposition who attends Ryujin Elementary and lives with his parents. He is energetic in sports, tends to be punctual, faces academic challenges, and holds a strong aversion to vegetables like onions and konjac. Wataru possesses a powerful sense of justice and refuses to tolerate bullying or deception against the vulnerable.

A pivotal moment occurs when he accessorizes a clay model from art class with magatama beads found at Ryujin Lake, inadvertently triggering a mystical event that transports him to another world called Shinbukai or Soukaizan via a dragon named Ryujinmaru. There, local inhabitants recognize him as a legendary savior, the reincarnation of a divine hero who saved the world from darkness millennia ago, a destiny tied to the bloodline of the Ikusabe Clan and his bonding with the guardian dragon Ryujinmaru.

His primary mission in Soukaizan is to liberate a seven-tiered mountain from an oppressive demonic ruler and restore color to a desaturated rainbow. This quest requires progressing through each tier, completing specific challenges, and defeating adversaries, incorporating elements reminiscent of role-playing games such as dungeon traversal and searches for magical artifacts.

Wataru has bounce-prone black-brown hair and a distinctive nose, often highlighted as charming. He habitually rubs his nose with a fist while frequently using the phrase, "To put it simply..." In his savior role, he wears a formal white and blue outfit with red and white shoulder pads, matching cuffs, a gold crown tiara, white footwear, and a broad sword in a red sheath.

His guardian partner, Ryujinmaru, is a mechanical entity brought to life through the fusion of the clay sculpture and a dragon spirit. This mechanized ally operates autonomously and battles opposing mechanized units called Mashins. Throughout his journey, Wataru forms alliances with natives of Soukaizan, including a kunoichi named Himiko Shinobibe and a samurai known as Shibaraku Tsurugibe.

Wataru aspires to become a Little League pitcher and an astronaut. His role extends into world-hopping adventures in certain narratives, paralleling other dimensional travelers, and his journey expands beyond Soukaizan to include subsequent adventures in stellar realms like Seikaizan, confronting renewed threats to the stability of the connected worlds.