aught

This was simply titled Illuminated. We don't really know if it's Byakuya (Kubo pls answer my Q, it's been 7 months). There's another Byakuya rkgk that immediately followed this with almost the same color scheme, suggesting both might have been drawn during the same period, just posted a month apart. (Illuminated on January, Golden Bya on February)

The fact that two Byakuya arts were posted one after the other threw me off if Illuminated was really Byakuya or if it was Jugram. But I'm mostly confident this is Byakuya because of the turtleneck from Coat Bya and the same color scheme + style as Golden Byakuya, though he has a different hairstyle and jacket from Coat Bya.

Zoom in

With logo at the back