Klein is a shut-in with nothing going for him in his life, sloth is his best friend. All that changes when one day he saves a girl from a couple of goons, but after that encounter he meets her again and finds himself captivated in her, but an unfortunate event led to both of them getting killed. Fortunately for him, he is reincarnated in another world called Artoria filled with magic, dragons....and such things. In this world he wishes to change himself in a meaningful way as he uses his power and old knowledge to impress everyone in that world, all while finding the truths of this new world and himself but........