The Count's Gun-Shooting Scoundrel

Special Forces agent K, who was betrayed by his colleagues while slaying monsters, opens his eyes to find himself as Arthur Julius, the scoundrel of a count from another world. “I want to live peacefully in this life.” However, a conspiracy by scum to swallow up his family awaits. “If you touch me, I’ll kill you all.” Arthur draws his gun and heads down the path to ruin! — Description from novelcodex.org