From Sidekick to Bigshot - Chapter 109 - They Must Pay the Price

Haruto Hayase was a normal high school boy in his third year, living a quiet life until his younger sister, Haruka Hayase, joined the same school. Haruka’s beauty and charm made her the center of attention, quickly becoming the school’s prima donna. But when a notorious gang leader set his sights on her, he did everything in his power to protect her—only to fail tragically. Haruka was brutally assaulted and tortured, and Haruto himself suffered an agonizing death. However, in a twist of fate, Haruto is given a second chance, waking up a year before the events that shattered his life. Armed with the mysterious ‘Debauchery System Slave’, he vows to exact revenge on those responsible. This time, he will use his newfound powers of the system and charm to seduce the loved ones of his enemies. From their mothers, sisters, and lovers to their closest friends, Haruto will make them his. His enemies will suffer as he steals what they hold dearest, ensuring their downfall in the most devastating way possible.

A young man was going about a normal day, and he went back home to his house being empty again, his parents had missed his birthday again.Just like all the other years before, there was nothing special about his 18th birthday it seemed.This however was far from the end, caught by something unexpected at his own house, he perished.It was supposed to be the end, however this only marked a new beginning.Faced with a great trial of will, and Karma, and passing with a score beyond anything else, he was given the Class Omni-Layer, and the Job Omni-Ruler along side a system to manage it all.All this to prepare him for a new world, a world of swords and magic, and classic isekai, but this world was anything except an easy trip.

At the end of the dark 40,000 years, the enemies in the Milky Way launched their final offensive. When the end of the Era comes, the eternal war will come to an end. The human empire has now reached its destined final moment.

But the gear of fate does not end. The fate of the Milky Way will be determined by him and them as it was ten thousand years ago. What will happen at the end of this dark 40,000 years?

- Description from novelbuddy

He crossed over to a new world where humans have magical power. They are called warriors. They use their power to kill the monsters that appear out of nowhere. Dragons, Dungeons, and Magic users are pretty common in this world. If you want to live in peace, you need to have that power. You can also become a powerful clearing dungeon.

In this dangerous world, he has a system that can help him grow stronger. But he didn't want to be a high-profile warrior who attracts much powerhouse attention or become a lab rat. He wants to be Low-profile and grow strong using his system.