Momotaros (モモタロス, Momotarosu?) is the first Imagin that gives Ryotaro his power, which allows for the Sword Form transformation. He can also sense when an Imagin is rampaging in the city, subsequently alerting Ryotaro immediately. His natural weapon as an Imagin is a sword named the Momotarosword (モモタロスォード, Momotaroswōdo?). Momotaros blames Ryotaro for his Oni-like form, though it matches his personality, best described as hot blooded, arrogant, and comedic, serving as a foil to Ryotaro's own shy and cowardly personality. In fact, Momotaros is more interested in fighting than carrying out the Imagin's goal. Unfortunately, he is constantly beaten by Hana when he gets Ryotaro into trouble. When he possesses Ryotaro, declaring the words "Here I come!" (俺、参上！, Ore, sanjō!?)[1], Momotaros's own personality takes over, giving Ryotaro power, confidence, and a bit of his eagerness for a good fight. His eagerness is shown in battle, where he always declares the words, "I am, from start (to finish), at the climax!" (俺は最初から（最後まで）クライマックスだぜ！, Ore wa saisho kara (saigo made) kuraimakkusu da ze!?). Momotaros is also somewhat selfish, initially fighting alongside Ryotaro in order to ensure his own survival. Though he unknowingly places Ryotaro in unneeded danger to suit his fancy, Momotaros eventually learns to respect him and his desire to protect others. Though he demands respect, Momotaros is usually put in his place by Hana and her powerful punches. He also does not know how to swim, has a narcotic reaction to red peppers, and seems to be afraid of dogs. While he acts hostile and demeaning to the other Tarōs, he does care about them, proven by hiding his anguish while they are slowly disappearing due to the events of the Climax Scene. Momotaros is the base for Den-O's Climax Form, as he has control of the head and torso and can control the other sections that the other Tarōs usually have primary control of if need be.Momotaros is voiced by Toshihiko Seki (関 俊彦, Seki Toshihiko?).
When insulting another Imagin, he usually calls them a "X-Jerk" (Ｘ野郎, X-yarō?) depending on the animal they are modeled after, or a shortened version. The other exceptions are Ryutaros, referred as "Brat" (小僧、ガキ, Kozō, Gaki?) or "Snot-nosed Brat" (ハナタレ小僧, Hanatare Kozō?), Deneb as "Tubby" (オデブ, Odebu?), and Teddy as "Tendon" (天丼?). Momotaros also refers to Hana as literally "Nosy Woman" (ハナクソ女, Hanakuso Onna?). He also puts emphasis on his final blow attacks, saying "My Finishing Attack, Part X" (俺の必殺技パートＸ, Ore no hissatsu waza pāto X?) while possessing Ryotaro in Den-O Sword Form, with a Part 1, 2, 2’ (Two-Dash), 3, and 5 (Ryotaro tells Momotaros that he skipped 4, but he considers not using 4 "cool", even counting from 1-10 while skipping 4). In his battle against Kamen Rider Gaoh, Den-O Sword Form swiped the Rider Pass over the Den-O Belt twice, initiating a doubled Full Charge for "My Finishing Attack, Special Edition" (俺の必殺技・特別編, Ore no hissatsu waza tokubetsu hen?). In his battle against the Alligator Imagin in Kamen Rider Decade, while empowered by Decade's Final AttackRide Card, Momotaros uses Kuuga Gouram and a DenGasher for his "My Finishing Attack, Decade Version" (俺の必殺技・ディケイドバージョン, Dikeido Bājon?). When performing his version of the attack in his physical form, he calls it "My Finishing Attack, Momotaros Version". His physical form is based on an oni and a peach and his DenLiner train features a dog, monkey, and bird, all of which are aspects of Momotarō (桃太郎?) the Peach Boy. Ironically, the legend has Momotaro's namesake defeating evil oni, while Momotaro is based on an oni.
