After taking time off, The Knight Sabers are back in action, thanks to a string of robberies performed by an evil organization called the Illegal Army, who takes up arms and destroys the peace in MegaTokyo.

A new type of Boomer with advanced AI is stolen! Now it's up to the newly re-formed Knight Sabers to get it back! However, they'll have their hands full with a group of Combat Boomers headed by a criminal scientist who is vying for the end of the Sabers.

Boomers all over MegaTokyo are rioting and throw the city into chaos. In order to stop this disaster, the Knight Sabers must locate the mastermind behind it all!