18 years old. Part-time worker at the cafe "Milk Dipper." A young man who transforms into Kamen Rider Den-O. He is a unique human known as a "Singularity Point," meaning he is unaffected by changes in time and can carry over his memories. He also has the ability to restore the flow of time based on his own memories. Hana recognizes this power and chooses him to be Kamen Rider Den-O. Though timid and plagued by terrible luck, he is a young man with a strong will and a kind heart.

A woman acting as a Guardian of Time at the Owner's request. Like Ryotaro, she is a Singularity Point. She became a crew member of the DenLiner after being displaced from the flow of time. She has a strong-willed, competitive personality and is serious and brave, unable to tolerate injustice.

The first allied monster (Imagin) to possess the protagonist, Ryotaro Nogami. He manifested from Ryotaro's mental image of the red ogre from the folktale "Momotaro." Short-tempered, quick to pick a fight, and foul-mouthed, yet he has a compassionate side and is easily moved to tears. He possesses Ryotaro's body (M-Ryotaro) and fights as the main personality of Kamen Rider Den-O Sword Form. He excels at grand swordplay using his dedicated blade, the "Momotarosword." Signature Phrases: "I have arrived!" "Here we go, here we go, here we go!" "Let me tell you, I'm at a climax from the very start!"

The second allied monster (Imagin) to possess the protagonist, Ryotaro Nogami. In contrast to the hot-headed Momotaros, he is always calm, composed, highly intelligent, and a womanizing playboy. He manifested from Ryotaro's mental image of the sea turtle from the folktale "Urashima Taro." He lives for lying and uses his silver-tongued, swindler-like charm to woo women. When possessing Ryotaro (U-Ryotaro), Ryotaro wears glasses and manipulates those around him (especially women) with eloquent words. He fights as the main personality of Kamen Rider Den-O Rod Form. Utilizing his dedicated spear, the "Uratarosrod," he excels in elegant spearmanship and underwater combat. Signature Phrases: "Would you like to be hooked by me?" "A thousand deceits, ten thousand lies. But my lies are, in themselves, the truth."

The third allied monster (Imagin) to possess the protagonist, Ryotaro Nogami. He manifested from Ryotaro's mental image of the bear from the folktale "Kintaro." His catchphrase is "It'll make you cry!" He is extremely sentimental and possesses a tremendous sense of chivalry, never hesitating to sacrifice himself for others. He usually dozes off in the DenLiner's dining car, but if he hears the word "cry" or "crying" (or anything that sounds remotely like it), he wakes up instantly and goes on a rampage, even if he was fast asleep. Possession of Ryotaro (K-Ryotaro): When possessing him, Ryotaro's hair grows long and his clothing changes to traditional Japanese attire (kimono). He displays superhuman strength and tries to solve everything through brute force. He fights as the main personality of Kamen Rider Den-O Axe Form. Using his dedicated axe, the "Kintarosaxe," he excels in heavy-weight power combat, taking enemy attacks head-on and crushing them. Signature Phrases: "My strength has made you cry!" "Wipe your tears with this."

The fourth allied monster (Imagin) to possess the protagonist, Ryotaro Nogami. He manifested from Ryotaro's mental image of the fox from "Kuzunoha's Parting" or the dragon from "Momotaro." His motif is a purple dragon. Originally, he infiltrated the DenLiner under someone's orders to assassinate Ryotaro, hiding deep within Ryotaro's subconscious. However, he fell in love at first sight with Ryotaro's older sister, Airi, promptly abandoned his orders, and became a companion (and freeloader) to Ryotaro and the others. When possessing Ryotaro, purple streaks appear in Ryotaro's hair, and he adopts a street-style fashion with a cap. He is always listening to music through headphones and performing light street dance (breakdancing), and he has the special ability to brainwash people around him into dancing along. He fights as the main personality of Kamen Rider Den-O Gun Form. Using his dedicated gun, the "Ryutarosgun," he features a tricky style of gunplay, firing bullets wildly and flashily while dancing, without any regard for collateral damage. Signature Phrases: "Can I defeat you? ...I didn't hear an answer!"

A young man who transforms into Kamen Rider Zeronos. He is the past self (at age 19) of the "Adult Yuto Sakurai," who is the fiancé of Ryotaro's sister, Airi. He was brought to the present to throw himself into the battle to protect time. He is cynical, foul-mouthed, and often displays an arrogant attitude, but at his core, he is a classic "tsundere" with a clumsy sort of kindness. His favorite food is shiitake mushrooms; if they are in a dish, his mood improves significantly. He rides the time train "ZeroLiner" and transforms into Kamen Rider Zeronos. Altair Form (Basic Form): A form characterized by sharp sword techniques, fighting with Yuto's own will. Vega Form: A form where Deneb possesses and merges with him. It unleashes overwhelming firepower from massive cannons on both shoulders. Zero Form: The strongest form, appearing as a rusted red. It is a harsh transformation where the price of the "Zeronos Cards" becomes even heavier. Signature Phrases: "Let me say this first. I am pre-tty strong!"

An allied monster (Imagin) who is the partner of Yuto Sakurai (Kamen Rider Zeronos). He manifested from the image of Benkei from the folktale "Ushiwakamaru and Benkei" and a crow. He has a warrior-like appearance with a green body and a cloak. He is extremely polite, meddlesome, and nurturing. He cares for the cynical Yuto more than anyone else and looks after him devotedly—from managing his meals to trying to make friends for him—much like an overbearing mother.