I hope somebody of MUCH greater knowledge manages to come across this. I only know a little of Buddhism and would love to learn what's behind this pic.
...though, to be honest, I admittedly thought of Hinduism. But, considering that this is Hijiri, I figured that wasn't right. Still not sure, though...
There are quite a few buddhist deities with multiple arms, but I couldn't find any with 16 arms. Still, my best guess would be that Byakuren is depicted as Juntei Butsumo Kannon or some other form of Kannon.
EDIT: Ok, I'm pretty sure it's Juntei Kannon. If you take a look at this from the same artist and compare it with Roku Kannon, it fits perfectly. More information about Roku Kannon and other forms of Kannon: http://www.onmarkproductions.com/html/kannon.shtml
It's probably Kannon/Guanyin,a deity of mercy,compassion etc. with thousand arms,and the artists just don't feels like drawing that many arms. Multiple hand beings exists in many cultures,Hindu mythos just have a particularly huge amount of weird beings,many of them have way too many body parts than common sense would dictates they should. Also,Buddhism (not original recipe) and Hinduism did come from around the same region,so they shared some common themes.