Also known as 사 채지간
Kim Sang-an, a cold-blooded loan shark. When his sister, a school teacher, takes her own life after being relentlessly tormented by her students… He becomes their new homeroom teacher to collect the “debt” of her life. A debt collector who would crawl into the depths of hell to get what’s owed, and students who are nothing short of demons. A brutal “teacher-student” relationship begins now.
30 Years Have Passed Since the Prologue 
A Corporate Underling Who Excels at Work 
A Dragonslayer’s Peerless Regression 
A Former S-rank Adventurer Who Was Betrayed By His Griends Because He Was Too Strong Wants to Live a Slow Life in The Countryside 
A Pig-Slaughtering Knife Cutting Through All Realms — Makes Sense, Right? 
A Rogue Guard in a Medieval Fantasy 
A Villain’s Will to Survive 
A Wimp’s Strategy Guide to Conquer the Tower 
A World Of Gold To You 
Absolute Regression 
Absolute Sword Sense 
Academic Supremacy Academia: The F‑Rank Supply Officer Reincarnates as the Legendary Greatest Mage