Toilet that allows users to check the cleanliness from the outside

Ban Shigeru this designed the toilet in the Yoyogi
Fukamachi Mini Park of Japan using a glass as exterior wall. He
said there are two important things when one uses
public toilet. The first is cleanliness, and the second is
whether anyone is inside’, he explained. He designed
the toilet that allows users to check the cleanliness
and whether anyone is using the toilet from the
outside using the latest technology, the exterior glass
turns opaque when locked and someone is inside using the toilet.