The "Regular" Serious Punch First Appeared In: One Punch Man manga chapter 36, "The Power of Boros" The first time Saitama showed off his first Serious Punch was during his fight with Boros.

In a serious fight between the two, Saitama is more likely to carry the day. Sung Jinwoo’s only chance is to stalemate Saitama using his abilities or by trapping him in a dungeon gate, but even ...

Saitama’s Serious Punch², His Mightiest Attack, Is Finally on Display In the one-minute-long video, One-Punch Man's protagonist, Saitama, unveils Serious Punch², one of his most famous abilities.