The Wandering Knight's Survival Manual

After dying due to an unexpected accident, Kim Yohan reincarnated as Johann Aitz of the prestigious Aitz Family. He may have been born a noble, but Johann Aitz ranks at the very bottom of the family hierarchy. To make matters worse, this world revolves around a ruthless medieval society. “The only person you can trust is yourself.” In a world ruled by the law of the strong, survival requires only two things: money and power. While training relentlessly using the knowledge he gained in his modern life, Johann ends up encountering Kaegal, the Master of Poison of the Empire’s greatest assassination guild, the Nesos Guild. This is the fierce struggle of Johann, who refuses to become just another prey of this brutal era. Source: MU