Saitama, the main protagonist in "One Punch Man," is so strong that in his battles in the first season, he only released one "normal punch" to take down his enemies. Reportedly, the upcoming season 2 will feature the strongest villain in the series and Saitama will have to ultimately unleash his "serious punch."

According to reports, if the anime adaptation of the continuation of "One Punch Man" remains faithful to the original manga series, fans will see that Saitama hasn't released his full power yet. The upcoming episodes will showcase the development of one of the strongest foes that Saitama has yet to encounter and, in essence, will also be the mirror image of him – a strong human (not a monster) that believes in himself.

[Spoilers ahead!]

If the upcoming episodes will reflect the events in the manga, Saitama will ultimately face a collection of the strongest monsters. This "Monster Association" is a team of Dragon- and upper-level monsters that band together to face the Hero Association. The Hero Association, learning of the monsters' base of operations, sends out a collection of A-Class heroes to exterminate them.

However, the base of operations turn out to be right under Saitama's apartment in the forbidden section of the city, prompting Saitama and his S-Class friends to join the melee.

The ending episode of season 1 for "One Punch Man" aired last December. With the latest releases from the original manga series being intermittent, it may take some time for the creation of season 2 to be finished. But fans may take advantage of "One Punch Man"-related content that will be released, such as a collection of OVAs that will showcase Speed o' Sound Sonic's training to ultimately defeat Saitama. There are also spin-off episodes that supposedly take place in the season 1 timeline but viewed from another character's perspective.