Right I'm new ish to the forum and been very quiet just keeping an eye out on everything, but what I'm about to say is all true and not crap. Im probably going to be the saviour of most peoples problems here as my mum is actually Japanese and iv asked her to translate what this picture says, this is a rough translation into english as some words on there don't translate to an english word:
Top heading- "Attenza"
1) Attach clips to the far end like fig 1
2) Have air vents all in the same direction like fig 2,
3) Attach clips on bottom vents like fig 3
4) Make sure vents are flat/ parallel. push button and this will release the spacer, make sure the spacer doesn't hit hazard button. Put protective sponge on top of spacer.
I think your right its for a drinks holder in the air vent, they are very popular in japan so your probably correct although it could be an ash tray as well?
Hope that helps man!