To take preventive measures against further atrocities caused by the Unidentified Life Forms, the police introduce the G3 unit. But when it is time to fight the murderous Pantheras Luteus, the G3 falls short to the power of Agito.

After the murders of the Saeki family, Makoto Hikawa decides to do some digging into the photo he found of the son, Nobuhiko. Halfway through his investigation two more "Unknowns" appear.

At the same time Shoichi Tsugami, who is trying to get along with his adoptive family, falls into a trance-like state and becomes the Kamen Rider Agito.