Saitama's speed in the manga is incredibly fast. It's hard to put a specific number on it, but he can cover great distances in no time and react with lightning speed to any threat.
Saitama's strength in the manga is basically off the charts. He has no known limits and can take down any foe with ease. His power seems almost invincible.
Saitama's strength in the manga is off the charts. He has no known limits and can overcome any challenge with ease. His power is so overwhelming that it often makes battles anticlimactic.
Saitama is a very powerful hero in the One Punch Man universe. He can defeat any opponent with just one punch. He has a simple appearance and a somewhat laid - back personality.
One way is to explore his life before he became a hero. Maybe he had a normal job and was constantly frustrated with the mundanity of it. This could have been the catalyst for his intense training.
Manga Saitama's progress speed is hard to define precisely. It can be rapid in intense moments but might slow down to flesh out details and relationships in different parts of the story.
His hair could also be a plot device in a more comical way. Imagine a situation where his hair has a mind of its own and keeps getting him into embarrassing situations. Like it gets stuck in a door right before a big fight, and he has to struggle to free it while the villain is making fun of him.