MTL - Attack Stream of Life - Chapter 44

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

A young man who had longed for stories of good and evil since childhood lost his life in a tragic accident and was reincarnated as a boy named Chrono Mak in another world.

He learned that in this other world, there is magic and witchcraft, and depending on how you train them, you can become as strong as you want to be, so he decided to become the strongest demon king in order to recreate the story of justice and evil he once dreamed of.

Ernest Quelt, the alchemist renowned for his unparalleled mastery of alchemy, has perished.But his death wasn't a noble sacrifice in battle, nor the result of a failed expedition—it was a betrayal. The very comrades he trusted most turned on him, driven by envy of his growing power.Yet fate wasn’t entirely cruel. With his final breath, Ernest's gaze fell upon the tube that contained his greatest achievement: a perfect artificial being known as the Homunculus.More than just a vessel resembling a human, this creation harbored the power of a catastrophic beast—one that had once nearly brought the world to ruin.

Being sucked into a fantasy world that nobody leaves doesn't sound half bad to Cain. He was a high school dropout with a drinking problem, living off disability due to his poor health, so it's not like he had much to lose except a few faithful friends he didn't talk to enough.

After a long night of drinking, Cain wakes up looking at what he believes to be the character creation screen of one of his beloved virtual reality games, but with no recollection of having purchased it. His unwitting choice to use the Random Character Creation option, unaware that the choice would be irreversible, sends him into this new world as a Puppet Master, a Summoning based class nobody else in the starting zone has ever heard of.

But as he soon realizes, this is no game, him and hundreds of others have been brought to another world with no instructions, no clear goals and no way home. It's a second chance to live a good life, but what will Cain be able to make of it?