His Gate target is Yuzuru Iijima, a boy who got into an accident after he rode a bike which belonged to his friend Akari Kurata without having the skill to do that. He has the abilities to control the wind, fly in the air, and other movements all including wind.
He first attacks Yuzuru using a horde of Ghouls. However, the Ghouls soon overpowered by Kosuke riding a bicycle, before he changes to Beast and defeats more Ghouls with his bike. When Sylphi will attack Yuzuru, he was halted by Wizard Land Style before retreat. When Yuzuru tries to ride bicycle, Sylphi uses the wind to make Yuzuru performs a incredible bike technique. In the next day, Yuzuru will show he can ride a bike to his friend, Akari Kurata. When Yuzuru almost finish the riding, Sylphi uses the winds to make Yuzuru fall from his bike, while his bike injures Akari. Kosuke soon change to Beast and fight Sylphi. However, Yuzuru blames himself for what happened to Akari and start to turning into a Phantom.
However, Yuzuru able to surprass his Phantom after seeing that Akari still alive. Though, Sylphi kidnaps Akari and later tell the magicians to trade Yuzuru for Akari. After Haruto, Kosuke with Yuzuru meet Sylphi, the Phantom brokes the the promise and will kill Akari, so Yuzuru may despair again. However, the third magician, which is Mayu uses the Gravity Ring and distract Sylphi and the Ghouls. Haruto and Kosuke soon change to Wizard and Beast. The two with Mayu (as Mage) keep defeated the Ghouls, before Sylphi escapes. However, he chased by Wizard Infinity Style and Beast Hyper, before defeated by the combination of Dragon Shining and Shooting Mirage. Though Sylphi already defeated, Beast would have to battles White Wizard, due to Yuzuru refuses to become a magician.
- Gate: Nishikawa
- Episodes: 40-41
- Destroyed by: Kamen Rider Wizard Infinity Style & Beast Hyper's Dragon Shining & Shooting Mirage
- Mythological Basis: The Sylph
- Height: 218 cm
- Weight: 127 kg
- Like Valkyrie before him, Sylphi is based on a mythological being that has been associated with females. However, sylphs have hardly any substantial mythos to their name.
- Sylphi is the first Phantom that defeated by both Wizard and Beast simulteneously.
- Sylphi's costume is modified from Hellhound's costume.