"One Punch Man" season 2 is currently rumored to premiere in early 2017, and when the show returns, it is going to see Saitama go up against some strong enemies, such as a returning Lord Boros. If the anime follows the plot of the manga source materials, then he will also be fighting the formidable Garou.
Back in September, it was announced that season 2 was officially moving forward, but no details about the plot or characters have been stated since then. Despite the lack of official news, fans of the two original manga series can point out what may happen if the anime closely follows the events of these source materials.
In the original manga by ONE, Saitama and the rest of the Hero Association had to deal with Garou. Garou was also known as the Human Monster, a being who was like Saitama in the sense that he had no super powers but trained so much that he had become almost god-like with his abilities.
Garou went on to hunt down the numerous members of the association, and because of this, the chapters were called the "Hero Hunter" arc. During this arc, several smaller, shorter story arcs were inserted to further develop the characters. One of these includes the origin story of Saitama's power.
When the manga was remade by Yusuke Murata, the "Hero Hunter" arc was expanded, and to this date, it is still an ongoing story. According to Inquisitr, it is possible that season 2 of the anime will be primarily based on the original "Hero Hunter" arc by ONE, but it may still borrow elements from Murata's version of the story.
Because of the short length of the ONE version and the incomplete nature of the Murata version, fans also speculate that season 2 may add in some filler episodes to fill in the gap. This may involve a feud between Saitama and his friend Genos and a rematch against the villain Lord Boros.
