After Passing Through The Book, I Snatched The Protagonist’s Master Bai Yueguang

Liu Yishu was struck by a thunderbolt and was thrown into the world of the novel he had just finished reading. There was also an inexplicable book-traveling system in his mind.
The small system forcibly assigned him the task of saving the relatives and friends of the protagonist Tiansha Lone Star, and threatened to kill him if he did not complete the task!
Who is trembling when a new-born little mythical beast cub faces a big demon with a great reputation in ancient times? Who is there again——
It is impossible to show off one's power, because Liu Yishu discovered that the first person he needed to save, the protagonist, Master Bai Yueguang, who died at the beginning of the chapter, turned out to be his enemy and creditor from ten thousand years ago - the kind of debt that was so big that even his life was not enough to pay it off!
Taking advantage of the other party's lack of memory, he decisively chose to hug his thighs. He first became a disciple, then asked for a promise of protection, and finally made a sacrifice to the world, successfully binding him to the protagonist's Master Bai Yueguang!
Later he realized that it is easier to invite gods than to send them away. Once you offend some people, you will never be able to get rid of them for the rest of your life!
This is a story about not paying back a debt, trying to take advantage, and finally getting yourself involved!