Sadly you may only hear from me yet again on this one. We are working from incomplete lists, which is why it's difficult to answer your question as to the proper name of this unit. Following copied and pasted from my post on the W.R. Japanese forum:
北 is an abbreviation for 北部 "Hokubu", which is what the Northern Army District was called. It was the deployment area of, and administrative area for 5th Area Army.
北9540 may be read as "北95" "40" which could mean it's a training or replacement unit. That said, still no idea what this unit's formal name was.
"北" (North) isn't a field army designation, it's for home defence units (who's members may still have day jobs), administrative offices and training barracks in the northern district. If I'm right about reading it this way "北95" "40" it looks like a training unit but if it's read "北9540" it looks like a home defence unit.
Wish I had more for you.
Edited by Rod, 15 September 2019 - 01:30 PM.