Explains Anything on Instagram: "Transparent public washrooms in Japan use polymer dispersed liquid crystal smart glass. When the toilet is unoccupied, an electric current passes through the glass, aligning the liquid crystal particles and making it clear so you can see if the stall is clean and empty. . . When the door is locked, the current stops, the particles scatter light, and the glass turns opaque to give full privacy even during a power failure. These toilets are part of the Tokyo Toilet