Sirius Lorelei is a half piranha Beastkin that is the little brother to Asrai Lorelei. For years, he has remained within her shadow. Though, yes, he would help her make the instrumentals of all of her songs that would grow wildly popular all around Ongaku, he never really gotten proper credit. He doesn't agree with what his sister is doing, but she's the only family that he has left. He's stuck in a very tricky spot with whether he should stick by his sister or follow his own morals. Perhaps the band could be able to convince Sirius to follow his heart.

As a character, Sirius is very intelligent, being a fellow inventor much like Quill. He is very unsure about what he should do, though, having not that great of social intelligence compared to his technological intelligence. He can come off as a bit awkward and weird to strangers, not really knowing how to talk without tripping over his own words. Sirius is typically a follower more than a leader.