Ore dake Level ga Agaru Sekai de Akutoku Ryoushu ni Natteita

A top player in a strategic medieval RPG, Ryuichi Hasegawa is reincarnated into the game as Erhin Eintorian, the villainous lord who dies in the prologue. Given a special ability to level up exclusive to him, he must use his knowledge of the game and this power to prepare for an imminent invasion. His domain will be attacked in one day, and he has no functioning military to defend it. Erhin must find a way to survive and avoid the fate written for him.