In 2020, unusual public toilets were installed in two parks in the ever-popular Yoyogi district of Tokyo and quickly, although for a brief period, became an internet sensation.

The stalls, in particular, are quite easy to find, encased by transparent glass walls of a variety of vibrant colors, looking immaculate—and yes, you read it right: the restroom's walls are transparent, totally see-through. You can see everything inside, from the flush toilet to the hand wash sink. Now the question is, how does one use it?

It's quite simple, actually. Once you go inside and lock the door, the walls automatically turn opaque, obscuring the user. The walls are made of glass covered with PDLC film, which renders them transparent when electricity is applied. Unlocking the door turns off the electricity, giving the glass walls its original opacity back.

The innovative design was conceived by Shigeru Ban as a response to the parkgoers' need for a safe and comfortable restroom, where one can be sure that the toilet is clean and that nobody is hiding in the stall. It's part of the ongoing THE TOKYO TOILET project led by the Nippon Foundation, which seeks to improve public restrooms across Shibuya City, making all of them accessible and comfortable while giving them a bit of artistic twist.

In 2023, the restroom was featured in the critically acclaimed Wim Wenders film Perfect Days, which follows the meditative life of a toilet cleaner in Tokyo.