Wataru Toki, known as Pepe Domani in Italy, is a timid 15-year-old residing in detective Kingorou Toyama’s apartment while aiding his investigations. His routine shifts when a time machine emerges in the attic, delivering Princess Karen—a descendant from his future union with girlfriend Koyomi. Tasked with securing the Jujaku phoenix to ensure peace for her Nandara Kingdom, Karen enlists Wataru and Koyomi in her quest, sparking clashes with Milenjo’s rival gang.

Karen awakens Wataru’s latent courage, enabling his transformation into Yattodetaman: a brash hero marked by theatrical flair, a flute, and a catchphrase. This bold persona contrasts his usual shyness. The metamorphosis involves chanting “courage” thrice, a time-stasis ray from Karen’s allies, accelerated training, and a rapid costume swap.

As Yattodetaman, he employs Rose Shurikens to target foes’ heads or attire and wields the Doremi Sword—a flute-polearm hybrid branding enemies with a “Y.” Partnering with Koyomi, he merges a key and heart-shaped lock to summon the Daikyojin mecha, a temperamental machine prone to overreacting to antagonists’ taunts.

Beyond his primary saga, he opposes the Dorombo gang in Time Bokan games and rivals Milenjo’s crew in a racing spin-off. A non-canon animated music video for Arashi’s “Believe” features a band member transforming into Yattodetaman, deploying his arsenal against adversaries.

His journey culminates in resolving Nandara’s crisis, though his post-adventure life remains unexplored. The narrative charts his evolution from insecurity to courage, sustained by external empowerment and alliances.