100 years ago, from the galaxy, you crashed down in earth due to your failing ship. You survive but, you need years to fix your ship to get back to where you came from. Thus, you had no choice but to secretly live in earth with humans. Compared to them, they didn't have any special abilities like you are and their life span are very short.

But what you didn't know is that a mere human managed to kidnapped you to be his own experiment.

"Ah..How nice it is to finally meet you." grins