Maou-sama no Machizukuri! ~Saikyou no Danjon wa Kindai Toshi~ - Volume 6 epilogue

Kieran was just an ordinary part-timer — a high school dropout who had also given up on boxing. With no parents and no real family, he survived by working his ass off every day. He was raised by a man he believed to be his father, but later discovered he wasn't — though the man passed away before the truth could fully sink in. What Kieran didn’t know was that he was actually the sole heir to a powerful business empire, the hidden son of a wealthy tycoon.

What the hell? That menace who bullied me since I was six years old, actually became a pretty girl after three years of living apart? And she even ran to our agreed duel location to confess to me, hoping that I can become her boyfriend?!

Ye Qinghan, young master of the powerful Ye Family, gets ostracized when his peerless father meets an unfortunate end. Lacking strength and in a bid to live a Purposeful life, he suffers through the unending ridicule, bullying and torture dealt to him at each turn. However fate is a cruel mistress and offers only pain and misery with no end in sight. Broken, weak and distraught, Ye Qinghan embarks on a journey to usurp the hands of fate and attain strength to protect his own.

Follow Ye Qinghan on his journey fraught with perilous encounters, betrayals and fortune as he seeks to overturn the heavens, defy fate and grasps his destiny in his arms.

- Description from Novelupdates

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.