MTL - I, The New Hokage of Konoha - Chapter 366 long-lost system

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

Hu Feng, a high school student, accidentally embarked on the road of modifying the world.

Riku Barusak is a hard-working child. Despite possessing an innate superior physical strength and having withstood harsh training she fails to unlock her talent as a spiritualist. The failure results in her being thrown away by her family.

Revenge is a dish best served cold, with dollop of whipped suffering and a sauce of acute humiliation.Karma would do anything to exact revenge on the one who was responsible for her mother's death, her father's disdain and distrust, and a miserable life.She was manipulated, maltreated, and humiliated by the one she trusted the most. Her stepsister!!Discovering she had only three days left to live, Karma would go to any length to exact revenge. Even offering herself to the scary and powerful demon overlord.A contract. Blood oath. Manipulation. Betrayal. And lots and lots of revenge.