For Genos, Saitama’s immense strength has always positioned him as both a hero and a figure to admire. Over time, however, Genos has started to recognize that while Saitama is unmatched in combat, he falls short as a teacher.
This realization forces Genos to confront an uncomfortable truth—he may never reach Saitama’s level of power, no matter how much he trains.

In One-Punch Man Chapter 186 (based on the Japanese numbering), Genos challenges Saitama to a sparring match, mirroring a battle they had early in the series. As Genos unleashes his attack, Saitama shuts his eyes, seemingly reacting to the flash of light.
This brief moment causes Genos to hesitate, recognizing that if Saitama truly saw him as a threat, he wouldn’t have reacted so casually. Despite all the strength Genos has gained throughout his journey, he remains unable to leave even the slightest mark on Saitama—something both of them are fully aware of.
The Distance Between Their Strength Cannot Be Closed
After pulling back from his attack, Genos starts to grasp the reality that Saitama never approached training him with genuine seriousness. Saitama has frequently insisted that his power isn’t something that can be passed down or taught, as even he doesn’t fully understand its origins.
When Genos asks Saitama whether he believes he has grown stronger, Saitama offers no real answer. The truth is, he hasn’t been monitoring Genos’ development like a true mentor would, and this realization is a difficult one for Genos to accept.
Recently, Genos had already been contemplating whether to leave the Hero Association in favor of the newly introduced Neo Heroes, believing that a change in environment could foster his growth.
The frustration stemming from his apparent lack of progress has only fueled this thought process, making the idea of a fresh challenge even more appealing. Despite Saitama’s indifference toward training him, Genos chooses to stay, unwilling to part ways with his mentor.
This decision indicates that even though he acknowledges Saitama’s shortcomings as a teacher, the bond they share and the feats Genos has witnessed Saitama accomplish are more important to him than formal training.
Though Genos isn’t entirely prepared to accept that Saitama may not be the right mentor, he has taken the first step in understanding that reality. At this point, his connection to the Hero Association is entirely tied to Saitama, meaning any disruption in their dynamic could prompt Genos to leave without hesitation.
This leaves open the possibility for an intriguing development in future chapters, but only time will reveal what path Genos takes.