Maoyuu Maou Yuusha - Volume 4 Chapter 7, “I am the Fearsome General of the Right of the Demon World.”

An orphaned boy with dreams of making it big through being a blacksmith is given a once in a lifetime chance to succeed when he's taken in by an odd pair - Eggor and Ella. While former teaches him the arts of craft, the latter teaches him the mysticism of cultivation, granting him two paths to tread in this life.

Chen Mobai, a third-year student of Xianmen No. 5 High School, is working hard to review and prepare for the entrance to Daoyuan. The direction of his efforts is: to develop a new world

- Description from novelbuddy

Jiang Chen travels to a fantasy novel world and becomes the villainous senior brother.He didn’t have any golden finger (cheat) and didn’t want to end up as villainous cannon fodder, so he repeated nine reincarnation cycles, only aiming to be an upright senior brother.Yet fate is unjust, bestowing upon him the aura of a villain, causing him to suffer countless misunderstandings and disdain.Until the ‘Tenth Life’!In this life, Jiang Chen gave up. His heart grew cold, and he also finally let himself go.Jiang Chen: “Since heaven wants me to be a villain, why should I defy it?”……My name is Jiang Lianyue, and I have a villainous senior brother who is despicable.I despise him, detest him, and even wish he would die quickly!But one day, I witnessed a flashback of nine lifetimes…In the first life, my senior brother sacrificed his own core to help the second brother rebuild his core, damaging his own foundation in the process.In the second life, I was afflicted with a cold poison, and my senior brother, with his modest cultivation, refined pills for a hundred days to cure me at the cost of destroying his own core.In the third life, I finally understood everything…

"Be my son's mother."