Kamen Rider: Mugen Kuuga!

In the 21st century, starting with Kamen Rider Kuuga, Kamen Rider has returned to people's attention again. Kuuga is the beginning of the new era of knights! Some people would say that the Kamen Riders that appear every year are always claimed to be the strongest, but in Ishimori's heart, the only strongest knight is his first Kamen Rider, the super-ancient warrior transformed by Yusuke the Fifth Generation - KUUGA/Kuga! On this day, Ishimori's fate changed, and an unknown system appeared. He became the ultimate villain, Dark Kuuga, and the knights became his enemies. All the knights disappeared, leaving only Kuuga transformed by the fifth generation Yusuke. "If I defeat all the knights, and Yusuke can get the power of all the knights, then I will finally fight Yusuke! No matter whether I win or lose, whether it is justice or evil, Kuaga will be the strongest!" Ishimori thought... System: "Ding! The knight after Kuuga will cease to exist, and the timeline returns to the turn of the century... This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.