Derek Seymour

Derek Seymour is Ashton's older brother within his home world and Derek Selby's incarnation from Kamen Rider: Chrono Warrior. He transforms into Kamen Rider A-King.

History
Like Ashton, Derek is also a Kamen Rider, setting up the operation to overthrow Fourteen. However, Derek was actually a double agent who worked to flush out the last two Kamen Riders of their world until Ashton unknowingly captured him, and as a result, played the role as Fourteen's puppet right hand in charge of the area management committee.

However, once Fourteen is destroyed, freeing everyone else from the brainwashing, Derek reveals the truth with intent to be the next Fourteen. In spite of not being able to kill Ashton, with Darren affirming he still has his free will, Ashton considers his brother dead to him and leaves.

Kamen Rider A-King
Derek transforms into A-King using the original Change Kerberos Rouze Card created in conjunction with the A-King Buckle, which utilizes the Club Warrior Buckle's Open Up system. He is equipped with the A-King Rouzer. By scanning the Mighty Gravity Rouze Card in the A-King Rouzer, A-King can perform the Gravity Slash finishing attack.
 * Height: 203cm
 * Weight: 100kg
 * Punching power: 300AP (3t)
 * Kicking power: 500AP (5t)
 * Maximum Jump Height: 35m
 * Maximum Running Speed: 100m/5 seconds

Equipment

 * A-King Buckle: Transformation device
 * A-King Rouzer: A-King's personal weapon
 * Rouze Cards: Allow A-King to perform special attacks