The air conditioner filters tend to get fairly clogged up from the Japanese smog and heavy smoking in the car.
Removal for cleaning is a very simple procedure with no tools required.
The first step is to remove the under glove box panel which is held in by two black plastic push-in clips at the rear and four hidden clips at the front. Remove the rear plugs then pull the panel down and towards you to release the front clips.
Looking up, remove the two wing nuts, though they might be in a slightly different position to those in the photo
Gently remove the filter bracket
Start sliding the filter straight down. The filter is actually in two sections with a fold in the middle. Once the first half is visible, fold it to the side and keep sliding downwards until the second half slides out.
Once you have removed the filter, look back into the slot and you will see the tab at the bottom of the second filter. You have to jiggle and slide it towards you in the slot, then slide it down and out the same as you did the first.
Clean the filters very gently with detergent, sugar soap has also been suggested. Optionally dose the filter with an air freshener.
When fully dry, carefully replace the filters by reversing the procedure, and check that the lugs on the bottom of the filter fit into the slots in the bracket.
The tab at the bottom is the start of the second filter.
Pictures plagiarised from Steve's Lexus Soarer Page which appears to now be defunct.