When you enter one of Tokyo’s new colourful public toilets and lock the door behind you something interesting happens. The jewel-like transparent glass walls of the facility become opaque, hiding both the interior of the space and its occupant from view. This is the first of many public toilets to be constructed throughout the city by the Nippon Foundation’s Tokyo Toilet Project. Shigeru Ban, the 2014 winner of the Pritzer Prize for Architecture, designed the attention-grabbing transparent toilets. His solution allows people to assess the facility’s cleanliness prior to entering. Project coordinator, Mihoko Ueki, says, “When the door is unlocked, an electric current runs through the crystals in the glass panels, creating a transparent effect.” By the summer of 2021, toilets designed by sixteen leading architects will be in operation in seventeen different Tokyo locations.