For those of you reading the redrawn version of Onepunch-Man by Murata, I should warn you that this is a review of the original Onepunch-Man comic by ONE which is much further ahead. So, if you continue reading, be wary of spoilers.
Saitama and Tatsumaki continue their battle throughout this chapter, rampaging across the country and stampeding into the stories of various side characters as they do so. We start with the introduction of the A-Class rank 34 hero Feather who is fighting to save his lover from N City's notorious Iron Fist gang headed by the A-class criminal Big Iron (none of whom we've ever heard of before). Just as Feather is about to have the heroic second wind to the biggest fight of his life, Saitama and Tatsumaki come crashing in, completely clueless, and offhandedly obliterate the gang. Afterwards, Feather justifiably decides to repress this memory.
We get reappearances of Metal Bat, one of my favorite S-rank heroes, and Speed of Sonic as well in similar circumstances, completely played for comedy. It was nice to see these two again, considering that Metal Bat hasn't been seen since the Alien Arc and Sonic since early in the Garou Arc, even though it doesn't seem likely they'll play much of a role any time soon.
ONE has been introducing a lot of A-rank heroes ever since the start of this arc, which I am pretty iffy about considering that the strongest three of A-class (excluding Sweet Mask) were shown to be pathetically weak compared to an S-rank towards the end of the Garou Arc. I have a hard time understanding just how useful these A-classes can be - even in this arc they've been pretty thoroughly humiliated (such as A-rank 35 hero Air being one-shotted by a severely weakened Evil Natural Water). It makes me wonder if ONE is just introducing them for the sake of filling out A-class when there are more plot centric things he could be using those panels for. However, since some of them, like Air, Butterfly DX, Chain'n'toad, and Forte, have been consistently appearing throughout this arc it does make me more confident that he has some plan in mind for them. Still, there were already plenty of A-rank heroes introduced before this arc,and reusing them probably would have been simpler than creating a whole bunch of new ones (although I suppose many of them might still be hospitalized after being hunted by Garou).
Finally, the battle between Saitama and Tatsumaki comes to an end, and Saitama, despite never going on the offensive at all, clearly has the upperhand. It's revealed, however, that Tatsumaki is still injured from her fights in the Garou arc (understandable since it was only a few days ago chronologically), but absolutely can't stand the thought of losing. When Saitama offers to postpone their fight until she's recovered, she smiles and happily agrees to see him later. Psyche!
At the end we return to Fubuki, who has agreed to Tatsumaki's demands by disbanding her group. It's likely that she's mainly doing this to protect them from her sister, but I don't think her subordinates are going to just let this be either.