Sirius is Weed and Koyuki's son, brother of Rigel, Orion and Bellatrix and one of the protagonists of GDW:Orion.

Kind and calm, he is more like his grandfather Gin and father Weed. Strong, brave and smart, he would often look after his siblings. He was named by Daisuke and made a brief appereance at the ending of GDW, as a newborn puppy.

In GDW:O, he is separated from his brother Orion by a volcanic disaster, followed by earthquakes that happened in Ohu. He found a shelter with Rigel, Bellatrix and Sasuke, who was their babysitter but he decided to go out to find Orion, getting lost. During the story, he sides with Kamakiri's three sons as they had found him and intend to use him as hostage but, later on, he is part of the small pack, not by force but because he wants to, since the three had saved his life.