Transparent
The scooter you made out of grains, and are about to ride down the stairs with, is completely transparent. You mashed the grains down so fine that you can see through them! And then you made them into a scooter.
Picture this transparent scooter. Well, it's actually a bit hard to see, because it's see-through. I guess imagine the outline and the feel, as you perch at the top of your stairs.
とう
す
None
You slip, the transparent scooter scoots down the stairs without you and into the streets of とうとうきょう. Nooo! Transpa-scootie come back!
Almost immediately you lose track of the scooter because it's transparent. All you see is とうきょう in front of you. And no scooter. Maybe this is why people don't make transparent vehicles.