Kamen Rider Yuuki

仮面ライダー幽汽

Kamen Rider Yuuki is the enemy Rider of the "Saraba Kamen Rider Den-O The Movie: Final Countdown" movie. He has two forms: the Skull Form and the Hijack Form. The theme of Kamen Rider Yuuki is death.

Shirou

死郎

Actor: Matsumura Yuuki 松村雄基

Shirou is the main antagonist of the movie. Shirou and his lover Sora lived happily together 400 years ago. When Sora died, Shirou was heart broken and couldn't stop thinking about her. He boarded the train of the dead, the Phantom Train, and obtained its Pass and the Yuuki Belt (ユウキベルト Yūki Beruto). He wishes to revive Sora, so they can live together once again. His plan is to have Nogami Ryoutarou (possessed by Ghost Imagin) to kill his own ancestors. Having a Singular Point erase himself from time could produce a destructive force great enough to turn time inside out. Living humans and dead humans would trade places. The dead will revive, and the living will die.

Theory from a Forum user:

When a normal person's ancestors are killed in the past, that person will simply disappeared from time. It would not create a paradox that turns time inside out. But because Ryoutarou is a Singular Point, anything that happens in the past cannot affect his existence in the future. And since he is a Singular Point from the future, killing his own ancestors will cause great confusion in the timeline. When a distorted timeline tries to repair itself from Ryoutarou's memory, the future (and everyone he remembers) will be restored and continue to exist.

So in a way, that time would both exist and not exist at the same time. That's where the living and the dead swapping would happen. Time would try to fix what it saw as wrong, because while Ryoutarou is alive, because his ancestors were killed he should be dead. In trying to correct itself according to Ryoutarou, the living will become the dead and the dead will become the living.

Ghost Imagin

ゴーストイマジン

Voice Actor: Kamiya Hiroshi 神谷浩史 / Suit Actor: Yokoyama Kazutoshi 横山一敏

Ghost Imagin is one of the followers of Shirou and abducted Nogami Ryoutarou under Shirou's orders. He possessed Ryoutarou and took control of his body, turning into G-Ryoutarou. With the Yuuki Belt G-Ryoutarou can henshins into Kamen Rider Yuuki Skull Form. Ghost Imagin likes to fight, and doesn't seem to care when his comrade Imagins are destroyed by Kamen Rider New Den-O. When fighting in Skull Form he uses Ryoutarou as a shield so the others cannot attack, and manages to deal severe damage to Kamen Rider Zeronos and corners the Den-O Imagins several times. Eventually, Momotaros is able to help Ryoutarou regain control and separate Ghost Imagin from Ryoutarou by taking a fatal blow from Skull Form. Ghost Imagin is destroyed by Kamen Rider Den-O Climax Form.

Ghost Imagin: Ghost Imagin is a green skeleton wearing a black cape. It is unclear which legend or fairy tale his design motif is based on and whether he has a contract holder or not.
G-Ryoutarou: In this form Ryoutarou's eyes are in light golden color. His hair also turns light gold with bits of green highlights.