Genos

Genos is the deuteragonist of One-Punch Man, a 19-year-old cyborg and the disciple of Saitama, always striving to grow stronger in his fight for justice. The Hero Association knows him as Demon Cyborg, and he currently holds S-Class rank.

Extremely serious and rarely one to joke, Genos constantly seeks Saitama's guidance and shows deep reverence toward him, referring to him as master. He both admires and envies his teacher, feeling real frustration that Saitama's absurdly simple training regimen somehow produced such extraordinary strength — a mystery Genos remains determined to uncover. Naturally calm but prone to overthinking, he's found that time spent around Saitama helps him relax, even as he keeps deploying advanced combat techniques and cybernetic upgrades that leave him battered in fights Saitama ends with a single effortless punch.