All I can say is my God,,,,why is this fucking addictive???
It's so damn good the farther the story progresses, especially the final arc( I think I the final arc)::: I'mspeaking at the manga side,not the anime; so I can spoil.
At first ,I feel like the hero association is just generic with dumb and hateable heroes like terrible tornado ,tank top black hole and tiger ( tank top master is Ok) just to name a few.
But as the story progresses,I get to understand their character.
As for our protagonist, Saitama, who ends a fight with one punch and becomes a hero just to find a worthy opponent, I find it lame but understandable since he became strong not by talent or hereditary power transfer but by hard work.
He lives an empty life since being a hero makes him bored till one day , Genos the cyborg witnesses his god- like strength and asks him to be his disciple.
Saitamas and Genos journeys to be heros is without a bumpy ride as they encounter elite s-class heroes in which some of them are cool like Silverfang. Atomic samurai .child emperor ,,,,,,whom I kidding all of them are awesomeness (except for King who is confused for Saitama as the strongest man in the world, instead is just an unemployed game loving otaku).
I must say this is the -it -manga and I really recommend it.
Character development -8
Art style - 9.25
Fights /action - 10
Plot - 8.75

Total score = 9/10