I'm at Level 30, But I Can Slay Level-9999 Beasts in One Hit! - Chapter 213: A Critical Moment

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.

Klein’s greatest wish is to transmigrate to another world and live life in an isekai, just like in anime, manga and novels. However, fate is on his side and the typical truck that the main characters always carry in isekai runs over Klein. But, to his bad luck, he lived a few more days in the hospital and, just on the day he died, Klein heard a ⟨⟨-DING-⟩⟩ that he knew it meant. That was the day of his death, but also the beginning of his adventure into another world.

On the wedding night, she was tied to his bed.

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates