Toji Kasuisai

Kasuisai Tosu: Japan's Most Celebrated Zen Temple Lavatory

Nestled within the sprawling grounds of Kasuisai Temple in Fukuroi City, Shizuoka Prefecture, the Kasuisai Tosu stands as one of the most extraordinary registered tangible cultural properties in Japan. A "tosu" is the traditional term for a lavatory in a Zen Buddhist monastery, and the one at Kasuisai is often hailed as the finest and most architecturally distinguished example in the entire country. Built in 1937 (Showa 12), this single-story wooden structure combines cutting-edge sanitary engineering of its era with the refined spiritual aesthetics of Soto Zen Buddhism. Today, it is a nationally registered tangible cultural property and one of the most photographed and talked-about structures in the Enshu region.

Historical Background of Kasuisai Temple

Kasuisai Temple, formally known as Banshosan Kasuisai, was founded in 1401 (Oei 8) by the Zen master Jochū Tengin. Over its more than six centuries of history, it has grown into one of the most important Soto Zen training monasteries in the Tokai region. The temple's distinctive name is rooted in a famous anecdote involving Tokugawa Ieyasu, the founder of the Edo shogunate. As a child, the future shogun had been sheltered at the temple while held hostage by the Imagawa clan. Years later, when Ieyasu invited the temple's 11th abbot, Senrin Tozen, to Hamamatsu Castle to express his gratitude, the elderly monk fell asleep during their audience. Rather than taking offense, Ieyasu affectionately remarked, "He may sleep" (kasuibeshi), and the temple adopted this phrase as its name.

In 1873, the fire-protective deity Sanjakubō Daigongen was transferred to Kasuisai from Akiha Temple, establishing Kasuisai as the head temple of the Akiha fire-prevention faith. The temple's vast grounds encompass numerous halls, gardens, and religious structures, and during the early Showa period, several ambitious building projects were undertaken to modernize the complex while preserving its Zen character. The construction of the Tosu in 1937 was part of this renewal, alongside the completion of the Zuiryūkaku guest hall in the same year.

Why the Tosu Was Designated a Cultural Property

The Kasuisai Tosu was registered as a national tangible cultural property on December 19, 2014, together with the Zuiryūkaku reception hall. The designation recognized the structure's exceptional blend of practical innovation and traditional Zen temple craftsmanship. At approximately eight meters square with a total floor area of 108 square meters, the Tosu is remarkably spacious for a temple lavatory. Its interior arrangement follows Zen monastic principles: urinals line the southern wall, individual stall compartments occupy the northeast face, and a raised platform at the center enshrines a statue of Ususama Myōō, the Buddhist deity of purification.

The ceiling treatment is particularly noteworthy in the context of Japanese architectural heritage. The peripheral ceiling features closely spaced lattice framework (fukiyose no gokubuchi), while the inner section is finished with elegant ajiro (wickerwork) paneling. A canopy-like decorative element crowns the center, and the transoms above the walls are adorned with intricate kumiko latticework. This level of decorative refinement in a utilitarian building is essentially unparalleled among Japanese temple lavatories and is a key reason for its cultural property designation.

Architectural and Cultural Highlights

What makes the Kasuisai Tosu truly remarkable is the seamless fusion of modern sanitation technology with the contemplative spirit of Zen Buddhism. When it was completed in 1937, flush toilets were still a rarity in Japan, and the installation of a fully plumbed water-closet system in a temple was considered a marvel of modernity. Visitors reportedly traveled from across the region simply to see this innovative facility.

The interior atmosphere is far removed from what one might expect of a restroom. The polished wooden floors gleam underfoot, and the ajiro dome ceiling casts warm, gentle shadows beneath a modern pendant light fixture — an original fitting from the 1930s that remains in use today. The overall effect is one of solemn elegance, a space that encourages mindfulness even in the most mundane of daily activities.

At the heart of the Tosu stands a towering statue of Ususama Myōō (Ucchusma), approximately three meters in total height, making it the largest such image in Japan. Carved by the renowned Buddhist sculptor Takamura Seiun, the four-armed figure stands in a fierce pose: the left hands point toward the heavens and hold a skull, while the right hands grasp a jeweled staff and a single-pronged vajra. The deity's right foot rests upon a great rock, and the left foot presses down upon a figure of Kangiten (the deity of bliss). The wrathful countenance, upswept hair, and necklace of jewels convey an overwhelming sense of sacred power. In Zen Buddhism, Ususama Myōō is venerated as the purifier of defilement, whose holy flames burn away worldly desires — a fitting guardian for the space where monks practice mindfulness of bodily functions as part of their spiritual discipline.

The Tosu in Zen Buddhist Practice

In Zen monasteries, the tosu holds a special significance far beyond its practical function. Together with the meditation hall (sōdō) and the bath house (yokushitsu), the lavatory forms one of the "Three Silent Halls" (sanmoku dōjō) — spaces where absolute silence must be maintained. This practice reflects the Zen conviction that every action, no matter how ordinary, is an opportunity for spiritual cultivation. Entering the tosu, monks are expected to maintain a state of mindful awareness, treating the act of physical purification as an extension of their inner spiritual practice.

The placement of Ususama Myōō at the center of the space serves as a constant reminder of this principle. The deity's origins trace back to Agni, the fire god of ancient Indian mythology, who was later incorporated into the Buddhist pantheon as a Myōō (Wisdom King) — a wrathful manifestation of the Buddha's compassion. His sacred flames are said to purify not only the spiritual impurities of the mind but also the physical uncleanness of the material world.

Visitor Information

The Kasuisai Tosu is accessible to all visitors who enter the temple's paid reception area. The lavatory is located adjacent to the Mansōkaku hall on the eastern side, near the main reception desk. Although it remains a functioning restroom — one of very few cultural properties in Japan that still serves its original purpose — visitors are welcome to enter, view the Ususama Myōō statue, and appreciate the architectural details. Photography is permitted inside the Tosu.

The temple grounds offer a wealth of additional attractions. The Zuiryūkaku, registered as a cultural property alongside the Tosu, is a magnificent two-story wooden reception hall built in 1937, with rooms decorated with themed fusuma paintings and transom carvings depicting cherry blossoms, wisteria, and other seasonal motifs. The Gokoku-tō (Memorial Tower), designed by the famed architect Itō Chūta and completed in 1911 to honor soldiers who fell in the Russo-Japanese War, is a striking reinforced concrete dome modeled on Gandhara Buddhist stupas and is designated a Shizuoka Prefectural Cultural Property.

Kasuisai is also celebrated as a "Temple of Flowers," with roughly 1,500 peony bushes of 100 varieties blooming from mid-April through early May, along with lilies in summer and vivid autumn foliage. The adjacent Kasuisai Lily Garden features two million lilies of 150 varieties across 15 hectares. Visitors can also experience Zen meditation (zazen), sutra copying (shakyō), and exquisite shōjin ryōri (Buddhist vegetarian cuisine) prepared by the temple's head chef, all available by advance reservation. Overnight stays at the temple's shukubō (lodging) offer a deeper immersion into monastic life.

Surrounding Attractions

Kasuisai is one of the Enshū Sanzan (Three Mountains of Enshu), a trio of historic temples in Fukuroi City that together represent a rich cross-section of Buddhist tradition. The other two are Hattasan Soneiji, a Shingon temple renowned for its yakuyoke (evil-warding) blessings and beloved dango dumplings, and Iōzan Yusanji, a temple associated with healing eye ailments whose grounds contain a nationally designated Important Cultural Property three-story pagoda and a mountain gate relocated from Kakegawa Castle. Visiting all three temples in a single day is a popular pilgrimage route. Each summer, the three temples jointly host the Enshū Sanzan Wind Chime Festival, filling their grounds with thousands of colorful wind chimes.

The nearby Kakegawa Castle, a beautifully reconstructed wooden castle, and the Kakegawa Kachōen (Flower and Bird Garden) are also within easy driving distance. Fukuroi City sits along the old Tōkaidō highway, and the surrounding area offers charming remnants of Edo-period post towns. For nature lovers, the Ogasa Plateau area and Ecopa Stadium complex provide green spaces for walking and outdoor activities.