One Punch Devil

I traveled through time and became the weakest force demon in the demon clan. He is only worthy of being a coolie, cannon fodder in wartime, and has five years left to live. Distressed, I could only learn Saitama's training methods. The demons laughed at this exercise method as a child's toy. Don't listen, don't listen, the bastard chants sutras. Number of exercises: ten times, one hundred times, one thousand times, ten thousand times, one hundred thousand times... Number of exercise days: ten days, one hundred days, one year, five years, ten years... Since then, I seem to have become too strong? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.