After being sent to a different world called Earth with a grinning grin by the elders, Gu Yun discovered that peace and stability were just the appearance of this world. In this city full of evil spirits and demons everywhere, what should his weak little sister do? So, Gu Yun made up his mind. He made up his mind. In order to make his sister healthy and happy, and to make her thrive. He decided to train his sister to be the strongest human being!