Kamen Rider Kuuga (2000)

During a cave excavation, the sealed Gurongi monsters are resurrected and begins murdering humans. When Yusuke Godai visits the cave during a police investigation, he sees a policeman carrying a stone belt found at the cave. He suddenly finds himself having visions of a warrior who fights the monsters. During an attack at the police station, Yusuke puts the belt on and becomes the warrior Kuuga. With his new power, he believes that he is fated to defeat all Gurongi monsters and put smiles to everyone's faces.