Help finding a sci-fi manga?

[madilynmoritz]

I remember reading a manga trilogy a while back and I'd like to read it again, but I can't for the life of me remember what it's called. It was three books, the main character was a human named Castiel (he was adopted by an alien race similar to humans). He was a general of some sort and forms a team of young heroes from a few teenagers in Japan in order that they can fight him because all his life he's dreamed of conquering the earth.
....Ring any bells? Thanks.

 

[Sarah]

Heroes Are Extinct!!

A surprisingly good and sadly, overlooked, sci-fi comedy.