In One-Punch Man, heroes protect civilians from harm against monsters, villains, and other threats. Most of them are registered with the Hero Association.
There are 4 types (classes) of heroes registered with Hero Association, C-Class, B-Class, A-Class and S-Class.
Heroes in S-Class are the strongest ones. Every of them is equivalent to an emergency army division, and can defeat disaster level Demon Mysterious Beings on their own.
Blast is a man with a muscular build.
A-Class heroes are the 2nd strongest of the four. They are capable of defeating disaster level Tiger Mysterious beings alone.
Sweet Mask is a handsome man, also a famous model, actor, and singer and is the most popular star in the world.
Heroes in this class,are capable of defeating disaster level Wolf Mysterious beings by themselves. They do not have to perform weekly heroic acts to fulfill any quota.
Fubuki aka Blizzard of Hell, is an esper, the leader of the Blizzard Group. She is among the few people who Saitama’s true power.
C-Class heroes are weak, but they exceed an average person’s strength. They must fulfill their weekly quotas by performing heroic acts.
Swim is a young girl who lacked confidence in her hero abilities. She is ranked the lowest in C-Class heroes, so one can know that she is not a strong hero.