I Was the Final Boss

21st Century Aggressive Male Lead Aggressive Protagonist Annoying Character/s Appearance Different from Actual Age Blood and Gore Blood-Thirsty Male Lead Censorship Cliches Cohabitation Comedic Moments in a Serious Manga Comedic Undertone Cult Dark Ambience Dark Fantasy Dark/Tan Skin Protagonist Dead Child/ren Demon/Monster Becomes Human Drug Abuse/Addiction Dungeon/s Extended Flashbacks First Time Dating First-Time Intercourse Flashbacks Flying Foul-Mouthed Character/s Full Color Game Elements God/s Grudge/s Handsome Male Lead Hunter/s Introspection Korea Loss of Power/s Male Demographic with Female Artist Male Demographic with Female Author Male Lead Falls in Love First Male Protagonist Modern Era Monster Reincarnated as a Human Monster/s Mysterious Character/s Nudity Pervert/s Piercing/s Rebirth Reincarnation Rich Character/s Romantic Subplot Roommates Ruthless Male Lead Ruthless Protagonist Self-Awareness Seven Deadly Sins Special Ability/ies Strong Character/s Strong to Stronger Strong to Weak System System Sidekick Terrorist/s Tower Climbing Tower/s Transformation/s Underworld Violent Male Lead Violent Protagonist Weak to Strong Webtoon