Taimanin Asagi RPGX: Twisted Gold

With the war against the demon faction of the Wraith King starting to look bleak, the lead medical and research staff of the Taimanin; Asakura Hatori, created the Juuga Driver, a part of the Chimera System weapons line to counter their demonic foes. However, the Juuga Driver denied any of the anti-demon shinobis to grant access to it's power, forcing the professor to rely on the weaker Chimera Driver. And during an attack by one of king's forces, the professor tried to protect his creation but his opponents proved to be too much for him.

But as fate would have it, a bypasser of the attack curiously equips the weapon and successfully transforms into Kamen Rider Juuga to fend off against the demons. Later joining the Taimanin, he promised to help them as long as he gets something in return, which usually involves with a very special kind of payment.