Naruto: Blake

Blake had been working in the shadows for his entire life. He had tortured, butchered, and killed for the sake of the greater good. Yet, he had not been rewarded for his sacrifice but had instead been betrayed. However, at the direst moment, when he thought that death was approaching, Blake fell into a portal. The Ruthless Heaven had descended. ---- (This is a weak to strong story about a former soldier in Naruto. He is constantly pushed to his limits and therefore gains greater strenght. Do note that mc has a system, though it's not wish fullfilment)