Jay id found 88927-53010 for the main filter
88926-53010 for the carbon filter
I think these could be discontinued though.
What I have found is this
This is a pollen filter from a vauxhall astra f or calibra its twice the length but the width is correct and its only 2mm thicker. I just cut it down and it fits really well. I got this one from euro car parts for £1.34 got to love there discount codes some days .
Liberally sprayed with my favourite watermelon car freshener to give a hit when the purifier is switched on plus it has got rid of that horrible japanese smoke smell the old filter had!
Usually dealer fitted optional extras don't show up in Toyota stock but it looks like the rear purifier was a factory option in the (super rare) Toyota Gita estate. You really can't get more obscure than that.