Darkwing

Darkwing is the Contract Monster of Kamen Rider Knight : Ren Akiyama.

Appearance
Darkwing resembles a Bat and is contracted to Kamen Rider Knight. Later in the Series, Through the Use of a Survial Card, Dark Wing evolves into Darkraider which is extremely powerful compared to it's Previous Form and can also turn into a Motorcycle for Knight's Final Vents.

Kamen Rider Ryuki
Darkwing, along with every other Mirror Monster was created by Yui's and Shiro's pictures during their childhood.

It is shown that Darkwing was initially used in one of Shiro's initial experiments and is assumed to be the Mirror Monster responsible for Eri going into a coma. Multiple times throughout the series, Darkwing acted as though it was targeting Eri. Each time Ren shooed it away. Most of the time however, it was there simply to assist Ren in battle.

With Ren's gain of a Survive Card, it allowed Ren access to Survive Form and hence, allowed Darkwing to evolve into Darkraider which is a much more powerful bat. This equipped Darkraider with Wind Turbines under his wings that could blow other Riders away. It also allowed him to turn into a motorcycle which Ren used to perform a Final Vent.

It is unknown what happened to Darkwing. But, considering, Mirror World didn't exist after the final Time Vent, it can be assumed that it didn't exist.

Kamen Rider Decade
To be added

Uses

 * Darkwing schreeches a high-pitched scream following the activation of a Nasty Vent which disorientates any opponent of Kamen Rider Knights'
 * Darkwing lends Kamen Rider Knight it's wings for protection when a Guard Vent Card is activated.
 * Darkwing bring's Kamen Rider Knight's Main Sword to him when a Sword Vent Card is Activated
 * Darkwing latches onto Knight and forms a Drill Shape for a Final Vent allowing Knight to piece an opponent with his kick.