Dragon Shadow Assassin

In the future, humanity no longer lives on Earth. Instead, humans live alongside aliens and creatures from myths and fantasy, as well as gods and demons, on a planet called T-108. Humans there all possess supernatural abilities, and some use these powers for shady dealings. Thus, the profession of assassin came into being. Assassins earn money by completing jobs and grow stronger. To save his non-blood-related younger sister, a boy named Long Xia takes on assassin missions to earn money. Gradually, he grows stronger and stronger.