Taros Brothers

The Rider Pass that Ryotaro Nogami uses to become Kamen Rider Den-O can summon at least four Imagin. Each of these Imagin gives Den-O their power when they are called upon with each form suited to their fighting style. These Imagin are collectively known as the Tarōs (タロウズ) due to their namesakes. When not possessing Ryotaro, the Tarōs spend their time in the DenLiner's dining car. However, they are also able to enter physical time and space by possessing vacant forms, such as full-body costumes, although this leaves them physically unstable. The Imagin have also proven capable of possessing Ryotaro all at once after the creation of Climax Form, but outside of their transformed state, this 4-way possession is dangerously unstable and physically stressful for Ryotaro. Due to their nature as Imagin, they can sense other Imagins near Ryotaro's vicinity and alert him to their presence. In addition to powering up Den-O, the four are each armed with a weapon and each are able to perform their form of Den-O's finishing attack in their normal state.

When the Junction Point starts to form, the Tarōs start to lose sync with Ryotaro and are unable to possess him when he travels to the past. To continue to assist him, they create the DenKamen Sword, which allows him to channel their power without direct possession. Though Ryotaro is curious of these recent events, the four are reluctant to explain that it meant the future they came from is being erased, causing their kind to cease to exist as the result of their battle with the evil Imagin. In spite of it, however, the Tarōs intend to keep fighting to the end, gaining physical form within normal space-time as a result of each Imagin granting Ryotaro's wish that they fight together until the end. When the time does come and they fade away, it is revealed that the memories they made with Ryotaro (a singularity point, and the primary Den-O) have created a time lag, allowing them to maintain their existence as they take leave on the DenLiner.

Soon after, the four become members of the DenLiner Police (デンライナーポリス), a newly-made law-enforcement group to prevent changes in the past by Imagin who also survived the Junction Point and form an army under Negataros. Because of their status as Imagin who fulfilled their contracts, the Tarōs are able to possess anyone as seen with Yuto, Wataru Kurenai, Tsukasa Kadoya, Yusuke Onodera, Natsumi Hikari, the Arms Monsters of Kamen Rider Kiva, G3, Ouja, Caucasus, Kotaro Nogami, Ankh and Daiki Kaito