No spoilers pls haven't finished reading, got a question

Just wanted to know if the Chapter 0 Vol. 0 was canon? Cuz some of the lines are diff from the official ones ig. Like Hikaru's words in the mountain from Ch.9 (?) and then this Ch.0 he says smth to 'Hikaru'/Brain snatcher to tell Yoshiki that he likes him (?) or smth since it was just a hint by incomplete words. Just wanna know if that actually was a draft/special chap by the author or by somebody else that was just uploaded here as well ;v;