After a long search in the archives I found volume 4 of the Mirage of Blaze manga.This version was in Chinese along with other mini stories that were published as specials by the Cobalt label editorial. These specials were published from time to time and exclusive from my perspective.
vol 4 is basically about takaya's childhood when he meets Yusuru Narita.
It is important to know that this content is from fans to fans, so you have to take care of the link.
https://dogemanga.com/m/0Ya6IdGR?l=en
It's a shame it's not translated in English.
Xy Lone
You could try using google lense to translate. While it's not perfect, it does give you a rough idea about what's going on.