Reborn as Eren Yeager: The Gacha System

I died without accomplishing anything. When I opened my eyes again, I was a newborn in a cruel world filled with man-eating Titans. My name was Eren Yeager. Just when I thought I had received a second chance at life, a mysterious voice echoed inside my mind. [Ding! Gacha System Activated!] [Welcome, Host.] Daily draws. Weekly draws. Legendary rewards. Skills from countless worlds. From swordsmanship and combat talents to mythical powers that should never exist in the world of Titans, every spin of the gacha could change my fate. Knowing the future, I refuse to watch my mother die. I refuse to watch humanity suffer. This time, I will rewrite destiny itself. But as the rewards become more powerful and the secrets of the world begin to unravel, I discover that Titans are not humanity's greatest enemy. The truth hidden beyond the walls is far more terrifying. Can a single gacha system change the fate of an entire world? Or will I become the monster destined to destroy it? — Description from novelcodex.org