Reborn As A Doomsday Villainess - Chapter 158: The library

Oosuki Masato is an ordinary high school boy who is magically transported to an alternative world, but for some reason his doting, over-protective mother comes along as well.

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

In a world where fate is scripted and power determines survival, Arthur Nightingale was never meant to shine.When he awakens in the world of Saga of the Divine Swordsman, he isn’t the destined hero, the villain, or even a major side character—he’s an extra. A nobody. A mere background figure in the shadow of Lucifer Windward, the overpowered protagonist who will one day ascend beyond gods.But Arthur knows the truth.The world he now inhabits is doomed. The plot is destined for a catastrophic downfall, and the so-called “geniuses” will not be enough to stop the tide of destruction. Armed with knowledge of future events and his own will to defy fate, Arthur refuses to be just an extra.