"Cover" (被り物, Kaburimono) is the 50th chapter of the One-Punch Man manga series.
Summary
At the Entertainment District, Muffintop is seen walking down the street with two ladies and trying to promote the Hero Association. He asks for a kiss from the ladies when suddenly Garou appears behind them and punches Muffintop.
However, Garou felt very dissatisfied from beating up the staff member. Saitama then appears behind Garou leading Garou to believe that a hero has decided to hunt him and strikes Saitama near the shoulder. This angers Saitama and retaliated by using the same move on Garou, thus knocking Garou out. As it turns out, Saitama was actually looking for a wig and no the hero hunter.
The next day, Garou wakes up on garbage with a fuzzy memory. Back at Saitama's home, Saitama tries out the new wig and Genos finds out about this and calls Dr. Kuseno immediately to give Saitama hair transplants.
Saitama was actually going to use the wig as a disguise for the martial arts tournament he was going to attend and invites Genos to come along.