Hidden skills movies?

Any movies you can recommend me that's  similar to "The Man from Nowhere " or at least has this sort of main character?

Basically a movie where the main character is hiding his identity or "skills"? 

or it can also be like the character underwent a process  ( maybe dieting, or learning how to fight or being really smart? ) and the people who knew him were shocked.

Non necessarily/specifically skills for fighting only, just special skills?

• Secretly Greatly - about a village idiot wjo is actually a spy
• My Papparoti - based on a true story of a troubled youth who came to surprise and make people cry with his unexpected skills
• Initial D - abput a dull and introvert highschooler who schools other drifters/racers
• Rurounin Kenshin - a poor normal looking wandering samurai who is actually a legendary assassin from the past era
• Beck - a bullied kid who finds his passion in music