Len

Len (portrayed by Matt Mullins) is a mysterious figure who is fighting Xaviax's monsters who has the ability to transform into Kamen Rider Wing Knight armed with a bat Advent Deck. He is aloof in personality and tries to keep the Riders' existence a mystery from the public. His Advent Beast is Black Wing, a bat. He is one of the original Kamen Riders from Ventara prior to their betrayal by his best friend Adam, the original Dragon Knight. At first, Len didn't want Kit to get involved with his problems or become Dragon Knight. But once Kit used the Advent Deck, they agreed to defeat Xaviax and save Kit's world.

History
While he vented Incisor without hesitation, he begins to start hesitating when he was confronted by Thrust and Sting hoping to save them and have them fight against Xaviax. Doubting himself, Len reflects and reminds himself that he is fighting in a war against Xaviax in which sacrifices must be made and that he cannot save everyone. He reflects on this again when Chris is vented, saying he shouldn't have been involved. He also feels pressure from being forced into a leadership role that he never intended to take, but resolves to carry out his mission regardless. Len and Kit are slowly developing a close friendship, possibly due in part to Kit being the Earth counterpart of Adam.

He was chosen to be a Kamen Rider at a young age due to his excellent physical condition, and considered it an honor to fight for Ventara. Recently, Len was re-united with Kase, Kamen Rider Siren and Len's girlfirend, who survived Ventara's destruction. He starts to notice that Kit is not being himself since Kase came back and thinking he needs some time, decides that when Kit is ready to become a real Kamen Rider, he can fight with them once more. After listening to Kit talk about his conversation with Xaviax as well as his resolve to fight against him, he welcomes back Kit as he accepts his offer to become a real Kamen Rider.

When Kit goes to talk to his father, Len and Kase sense Strike and Wrath. He finds that Xaviax has hijacked Wrath's body to directly fight him, something which insults Len since the original Wrath was his mentor. They are overpowered by their combined force but escape before they receive any more injuries. During their next encounter, he was able to turn the fight on Wrath, but let him go to find Kase and Kit. When Trent gives him the location of the No-Men, Len and Kase break into the building to rescue Kit. They find Kit being attacked by Strike and Wrath and successfully retreat with Kit. Kase shows Len his Survive card and soon they go off to fight Wrath and Strike. However, JTC manages to steal the Thrust and Sting decks from him only to use those two decks against them.

After a long battle, with the group severely weakened, Strike manages to vent Kase. Losing his girlfriend twice to the war, Len chooses to go after Strike with nothing but revenge on his mind. He immediately triggers Survive Mode, and after a short battle with JTC their Final Vents collide, taking Len out of Survive Mode but venting Strike in the process. Wrath shows up and and takes on both Len and Kit in their Survive Modes. Wrath proves to be too strong as he overpowers both of them and in the process vents Kit and Vic, but the body of Xaviax is unaffected. History repeats itself as Len once again becomes the only Rider remaining in the war against Xaviax. When all hope is lost, Len acquires a letter from Michele Walsh and says that they can still win the war.