One-Punch Man, Vol 4.

A manga series that packs quite the punch!

Nothing about Saitama passes the eyeball test when it comes to superheroes, from his lifeless expression to his bald head to his unimpressive physique. However, this average-looking guy has a not-so-average problem-he just can't seem to find an opponent strong enough to take on! Saitama is now a certified hero! And with that title comes great responsibility-he's required to perform one heroic deed per week. While Saitama makes the rounds to meet his quota, and incoming threat from outer space is screeching toward Earth...