MTL - Billion Technology Crystal System - Chapter 6 : Cranky brother.

Arriving in a fantasy Otherworld, Gauss obtains an Adventurer's Handbook that grows stronger the more monsters he slays and collects. Gauss originally thought he was embarking on a classic adventure to defeat the Giant Dragon, kill the Devil, and save the kingdom. Yet, seeing goblins breeding like pests and multiplying endlessly, along with the fast-growing kill count and rewards in the Monster Atlas, his face grows increasingly helpless...“You have slain 1000 goblins! Intelligence +1, Strength +1, Constitution +1.”“The title 'Goblin Slayer' has upgraded to 'Goblin Expert'. You are an expert on goblins; few know better than you how to kill them.”“...”“The title 'Goblin Expert' has upgraded to 'Goblin Star Destruction'.”

When a person dies, they either die light as a feather (aka unimportant) or heavy as Mt. Tai (aka very important).

DEATH COULDN’T KILL HIM—IT JUST GAVE HIM A NEW LIFE TO DESTROY.Reo Carter was a name that made even the hardest killers shudder. A perfect hitman—no hesitation, no mercy. Until his own crew turned on him, leaving him bleeding out in a pile of bodies that used to be his enemies.But fate wasn’t done with him.He wakes up in a world of nobility, magic, and honor duels—trapped in the body of Leonhardt Caulem, the weakest, most useless son of Duke Caulem. A spoiled brat with no skill, no spine, and a reputation so pathetic that even servants look down on him.They think he’s weak? They have no idea who they just brought back.- Swords and magic? He spent his last life dodging bullets—this is child’s play.- Dueling etiquette? A knife in the ribs is the only honor that matters.- A noble’s life of luxury? He’s had enough backstabbing for one lifetime, thanks.He was once a ghost in the underworld—a man who didn’t exist. Now, in a world where strength is everything, he’s about to remind them what true fear looks like.The hitman is back. And this time, he’s aiming for something more.#NobleByDayKillerByNature #TheyBroughtBackTheWrongMan #FromHitmanToDuke #SayYourLastWords

The King of the Underworld returns, and due to a marriage contract, he comes back to the city to marry, only to meet his ice-cold wife. Surrounded by numerous admirers, including a former first love, a beautiful colleague, and a cute lolita... As skilled enemies attack, watch how the King of the Underworld responds.