Yagami Arian was originally a soldier under Nelle Poe who fought for Mars independence during the Pan-Galactic War, where he was apparently part of a vast battle in which he was either the only survivor, or one of very few. He is nicked-named "The Reaper" because of the many RBs he has destroyed, and the coldly efficient way he operates; early in the series, he informs Elizabeth that "I just don't know how to hold back."