MTL - Devil - Chapter 14

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

Nagi Travers, a 20-year-old shut-in and former gaming champion, lives a miserable and isolated existence after being tormented by bullies throughout his life. Fired from his last job and grieving the loss of his parents, Nagi now survives by playing video games and barely ventures outside. His world spirals further into despair when he encounters Jake and Mary, his former high school bullies, who humiliate him and steal his money.Broken by the return of his tormentors and the weight of his past, Nagi contemplates suicide as his only escape. Just as he’s about to take his life, a small girl’s ball rolls into the street, with a speeding truck barreling towards her. In a moment of selflessness, Nagi rushes out and saves the girl, sacrificing himself in the process. Fatally injured, he reflects on the idea that it's better to die doing good than bad.Nagi awakens in a surreal, white world, where he is greeted by an angelic figure who offers him two choices: remain in eternal peace, free from suffering, or be reborn in a different world where he could seek redemption and a second chance at life. Nagi faces a life-altering decision—rest forever or attempt to find meaning and fulfillment in another world.

Before he was a little over 10 years old, he was the nightmare of the Gorge of Heroes and the headache of countless people that had been abandoned by the world.

After leaving the Gorge of Heroes, he became a legendary figure of the number one academy in the continent, and he alone brought numerous changes to it.

Thereafter he stepped foot onto the continent to become a legend, but the road to become a legend was far more difficult than he’d imagined….

On a continent where puppet masters reign supreme, using anything and everything as weapons: living creatures, shoes, daggers, pendants, clothes, shields, guns — which they call puppets, this is the story of Bai Xiaofei with his trusty sidekick, Huskie, on a quest to find out exactly what happened to his parents and become the greatest illusion stream puppet master the world has ever seen. This is a story of wit, plot twists, love, strategy, cultivation, humor, and the unknown.

Stealing Heroine from Protagonist with SystemWARNING MATURE CONTENT!!!!!R-18