The Disappearance of Demon Cyborg

A mysterious force brings Genkei crashing to the present after his family is killed by the Mad Cyborg. He meets up with the most powerful superhero Saitama and his cyborg disciple Genos. Together they try to understand how Genkei got there and how they can send him back, but the young teen doesn't want anything to do with Genos, seeing how he now hates all cyborgs.