I don’t really want to spoil the story, but I’ll say it anyway: He is not Sirius. . . Of course, this is not a spoiler. The previous chapter wrote about this, but it didn’t mention why He thought he was Sirius.

Also, Xia Feng is Sirius because he is bound to Mu and synchronized with Mu. I think everyone has forgotten this. So Xia Feng is not the original Sirius, Mu is. For details, see the beginning of the book.