Japan has devoted an extraordinary amount of ingenuity to the business of going to the bathroom. Its toilets can warm themselves before you sit down, adjust the temperature and pressure of a stream of water, disguise embarrassing noises and occasionally open their lids as though welcoming you home. There are public bathrooms designed by Pritzker Prize-winning architects, toilets that respond to voice commands and, at a rural railway station in Chiba, a single glass cubicle surrounded by an entire private garden.

Japan's high-tech toilet revolution began, somewhat unexpectedly, with an American medical device. In 1964, TOTO began importing the Wash Air Seat, a warm-water washing attachment developed for people with conditions such as hemorrhoids. The technology was temperamental, with inconsistent water temperatures and an uncomfortable spray, but the company believed it could find a wider market.

Developing its own version required some rather intimate research. TOTO recruited more than 300 employees to help determine the most comfortable position for the water jet, eventually settling on a 43-degree spray angle, which the company dubbed the "Golden Angle." Engineers also established preferred temperatures of approximately 38°C for the water and 36°C for the heated seat. In 1980, the first Washlet went on sale.

In 1982, TOTO enlisted Jun Togawa, the wonderfully eccentric singer who would become an icon of Japan's avant-garde music scene, for a television commercial. Togawa smeared blue paint across her hand and attempted to wipe it off with paper, demonstrating a fairly persuasive argument for washing instead. The slogan, Oshiri datte, aratte hoshii, translates roughly to "Even your bottom wants to be washed."

By 2020, more than 80% of Japanese households owned a warm-water washing toilet seat, according to government figures cited by TOTO.

Perhaps the most revealing Japanese bathroom invention, however, was designed to address an entirely different problem: embarrassment. For years, some women in Japan would flush public toilets repeatedly to conceal the sounds of using them, a practice that became particularly concerning during the country's chronic water shortages. In 1988, TOTO introduced the Otohime, or "Sound Princess," which plays artificial flushing sounds without wasting actual water. The company estimates that installing the device in an office with 400 female employees could save approximately 3.39 million liters annually, depending on usage. The name was reportedly conceived by a female developer, combining the Japanese word for sound with a reference to the mythical princess Otohime. Modern versions can even play birdsong, should the sound of imaginary running water prove insufficiently soothing.

For all this technological sophistication, Japan's public bathrooms still had a reputation for being dirty, smelly and unpleasant. Beginning in 2020, THE TOKYO TOILET project set out to change that, commissioning 16 creators, including Tadao Ando, Kengo Kuma and Shigeru Ban, to redesign 17 public toilets across Shibuya.

<Image: Haru-no-Ogawa Community Park toilet by Shiger Ban. Courtesy of Satoshi Nagare>

Ban's contributions are among the most extraordinary. At two parks in Yoyogi, he installed brightly colored glass bathrooms that remain transparent when empty, allowing visitors to check whether they're clean and unoccupied. Lock the door, however, and the glass turns opaque. At night, the illuminated structures resemble enormous lanterns, provided you're willing to place that much faith in the technology protecting your privacy.

<Image: Nanago Dori Park toilet by Kazoo Sato. Courtesy of Satoshi Nagare>

Elsewhere in Shibuya, creative director Kazoo Sato designed a white, dome-shaped toilet at Nanago Dori Park that responds to voice commands. His inspiration came from research into the lengths people go to avoid touching public-bathroom surfaces, including opening doors with toilet paper and flushing with their feet. Visitors can operate key functions without using their hands. The concept predates COVID-19, although the pandemic made its appeal considerably easier to understand.

<Image: Bathroom in Nature by Sou Fujimoto. Courtesy of Iwan Baan>

In 2012, architect Sou Fujimoto designed a glass-walled women's restroom at Itabu Station in rural Chiba, surrounded by a private, 200-square-meter garden. Dubbed the "world's largest toilet," despite containing only a single fixture, it offers views of flowers, trees and countryside, while a two-meter-high fence keeps passersby from looking in. Fujimoto later contributed a separate design to THE TOKYO TOILET, featuring a monumental public washbasin.

Shibuya's architect-designed bathrooms eventually attracted the attention of German filmmaker Wim Wenders, who was initially invited to make four short documentaries about THE TOKYO TOILET project. Instead, he made Perfect Days (2023), a feature starring Koji Yakusho as Hirayama, a man who cleans Tokyo's public toilets with extraordinary care. The film follows his daily routines, lingering over the small gestures and meticulous work involved in maintaining these unusual spaces. Several of THE TOKYO TOILET's architectural showpieces appear throughout the film, though Wenders devotes as much attention to the work of maintaining them as to their designs. Yakusho won Best Actor at Cannes, and the film received an Academy Award nomination for Best International Feature Film.

It's a remarkable trajectory for a collection of public bathrooms, and a fitting addition to a country where even the most ordinary bodily necessity has inspired decades of invention, architectural experimentation and, apparently, cinema.