Imagin
The Imagin (イマジン, Imajin) are a fictional race that serve as the antagonists in the Kamen Rider Series Kamen Rider Den-O. The name "Imagin" comes from several words in the English, Japanese, and even Arabic languages: "imagine" (イマジン, imajin), "now" (今, ima), "person" (人, jin) and "djinn" (ジン, jin).
The Imagin were designed by Yasushi Nirasawa (韮沢 靖, Nirasawa Yasushi), who previously worked on the designs for the Undead in Kamen Rider Blade, the Horrors in GARO, and the Worms in Kamen Rider Kabuto. These designs are detailed in Imagin Works: Say Your Wish... (イマジンワークス SAY YOUR WISH..., Imajin Wākusu SAY YOUR WISH...).
Background
The Imagin are beings from a possible future who have lost their physical forms due to an event that erases their timeline, becoming dependent on existing through the memories of humans, though this event and timeline are not well explained. Led by Kai, they arrive to the year 2007 to find weak-hearted humans and through them go back in time to find the key figure to the Junction Point (分岐点の鍵, Bunkiten no Kagi), and destroy him so their future can become a reality again. Imagin possess humans upon forging a contract, fashioning a physical form by searching through the host's memory for figures found in folklore and myths. In some cases of Imagin possession, a person's eyes change color to that of the Imagin, the hair altered into style with a streak of it also changed to the color of the Imagin. In some cases, even the host's attire changes to reflect the Imagin's personality. There are also rare Imagin showing the ability to split into two or more entities that can survive independent of each other. Normally, when this happens, there is a clear difference between them, ether physical or they'll have completely different personalities. Unlike most Kamen Rider villains, who normally have greedy or selfish motives for their actions, the Imagin attack the past due to self preservation, wanting to keep their race alive.