History's Strongest Son-In-Law Living With The In-Laws - Chapter 680

Yuki, a high school junior, dies heroically saving a stranger and is reincarnated in a fantasy world, where he discovers an extraordinary and unrivaled power.

“How many people have you killed? How many families have you destroyed? How many towns and cities have fallen because of you!?”“I don't remember.”The villain whom the main character was destined to defeat at the end of the novel. That was who I had become.There was just one problem...“Why am I a teenager!?”“Why is there a school acceptance letter on my desk!?”

A prestigious senior mechanical engineer in the industry, Xu Yi was sent to a world dominated by magic.

In a world with an almost non-existent industrial system, how can Xu Yi display his value?

When magic collides with modern technology, when magic merges with machinery, that is the beginning of this story.

In order to chase down and kill her own murderer, Xia Yichu reached an agreement with the 233 system, and she will travel through the world to complete the task, and The 233 system helped her return to the original world.
However, Xia Yichu often encountered a broken BOSS while he was on his way to do the task. He did n’t agree with each other on the wall, the bed, the various patterns, and kept talking.
System: Please use one word to describe the other person’s impression in your heart.
Xia Yichu: Competent.
Shen Jiaye: Mine.

- Description from 69shu