Saitama (サイタマ Saitama) is the main protagonist of OnePunch-Man, and the most powerful hero alive. Having apparently trained himself to superhuman condition, Saitama faces an existential crisis as he is now too powerful to gain any thrill from his heroic deeds.
He is registered with the Heroes Association as a C-Class Superhero and is tasked to defend Z-City against Mysterious Beings.
For a superhero, Saitama is rather laid back. Because even the mightiest foes pose no challenge to him, he doesn't take his hero work very seriously. In spite of this, he is constantly searching for an opponent that can challenge him, since his superhero work is beginning to bore him because it's too easy. The combination of his attitude, unstoppable strength, and distinctively simple and 'unimpresive' appearance often cause his battles to become anticlimactic. Saitama will usually allow his opponents to rant about their motives and power up into their strongest forms before suddenly and nonchalantly obliterating them with one punch.

As a character, Munsu's looks match his personality; rough, but efficient. He wears a pair of tall black boots with rolled up jeans. At the top he wears a heavy blue coat decorated with belts, straps and buttons with a simple brown scarf touching it up.
On the outside, Munsu appears as a very cruel and blunt street-enforcer, who takes no sympathy and gives no pity. He is crude and sometimes his tactics can almost hit on a borderline "evil." This however is all something of a misinterpretation. Deep down, Munsu is a wounded and troubled soul who has learned not to trust anyone as they are bound to hurt him eventually as his past has taught him. He does not believe in miracles, but only in using one's head, and more specifically, blunt "coincidences." He is extremely arrogant and cocky in his abilities, but at the same time, is well aware of his capabilities; he makes no effort in showing humility in his own abilities in the face of his enemies.