Beg Me to Remarry - Chapter 578 - 579 The Use of Bodyguards

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

The world where the Hero and the Demon King continue to oppose each other. The grand magic from the Hero and the Demon King cross over worlds and exploded in the classroom of a certain high school.The students who died in the explosion will be reincarnated in a different world. The protagonist, who had the lowest reputation in the class, was reincarnated into a spider. Nevertheless, she adapted quickly to the present condition with strong willpower.This is a story of she who has become a spider trying whatever she can to live.