Unlocking the Mystery of Koshin-to Stones
If you wander off the neon-lit avenues of Tokyo and step into the quiet backstreets of Japan’s countryside or historic districts like Kamakura, you might encounter strange, weathered stone pillars standing silently at crossroads. These are Koshin-to (庚申塔), ancient monuments that offer a fascinating glimpse into a folk religion that once dictated the sleeping habits of an entire nation.
Often adorned with the famous “Three Wise Monkeys” covering their eyes, ears, and mouth, these stones are not just garden decorations. They are spiritual sentinels, erected centuries ago to protect communities from a very specific, and somewhat terrifying, supernatural threat. For the culturally curious traveler, understanding Koshin-to unlocks a hidden layer of Japanese history, blending Taoism, Buddhism, and Shinto into one unique faith.
Origins of the Koshin Faith
The Koshin faith, or Koshin-shinko, is a complex syncretic belief system that originated in China but evolved uniquely in Japan. Its roots lie in Taoism, specifically regarding the sexagenary cycle—a system of measuring time in 60-day units.
The word “Koshin” refers to the 57th combination in this 60-day cycle, known as Kanoe-Saru (Metal Monkey). The belief arrived in Japan as early as the Heian period (794–1185), initially practiced by the aristocracy before spreading to the samurai class and eventually the common peasantry during the Edo period (1603–1867). It was during the Edo era that the massive proliferation of stone monuments—the Koshin-to—began. These stones were erected by local community groups, known as Koshin-ko, to commemorate their dedication to the rituals required to stay safe from divine judgment.
The Legend of the Three Corpses
Why were these stones built? The answer lies in the Legend of the Sanshi, or the Three Corpses.
According to Koshin belief, three spiritual worms live inside every human body. These aren’t physical parasites, but supernatural entities. For 59 nights, they remain dormant. However, on the night of Koshin (occurring once every 60 days), a mystical event takes place. If the host falls asleep on this specific night, the Three Corpses leave the body and ascend to the heavens to report the person’s sins to the Heavenly Emperor (Tentei).
Based on this report, the Emperor would shorten the individual’s lifespan. To prevent this, the Japanese developed a practical, if exhausting, counter-measure: Don’t sleep.
This ritual was called Koshin-machi (Koshin waiting). Villagers would gather in a designated house, usually rotating among the group members, to stay awake the entire night. They would drink sake, chant sutras, and socialize until dawn. By staying awake, they trapped the Three Corpses inside their bodies, preventing the report of their misdeeds and thus extending their lives. After performing this ritual for 18 consecutive Koshin nights (about three years), the group would erect a memorial stone—the Koshin-to—to honor their achievement.
Koshin-to in Modern Culture
While the strict practice of staying awake all night has largely faded from modern Japanese life, the Koshin-to stones remain as ubiquitous historical landmarks. They serve as open-air museums of iconography.
The Blue-Faced Vajra
The central figure on many Koshin-to is Shomen Kongo, a fearsome, blue-faced deity from Buddhism who was adopted as the protector of the Koshin faith. He is often depicted with multiple arms, holding weapons to ward off illness and demons.
The Three Wise Monkeys
Beneath the deity, you will almost always find the Sanzaru—the Three Wise Monkeys.
- Mizaru: Sees no evil.
- Kikazaru: Hears no evil.
- Iwazaru: Speaks no evil.
While the West views these monkeys as a proverb about integrity, in the context of Koshin, they served a magical function. They were meant to symbolically block the eyes, ears, and mouths of the Three Corpses, or perhaps prevent the Heavenly Emperor from receiving the negative information about the humans. The monkey is also the zodiac animal associated with the Kanoe-Saru day.
The Rooster and Hen
You may also see carvings of chickens on the stones. These represent the dawn—the moment the Koshin night ends, the danger passes, and the weary worshippers can finally sleep.
Traveler’s Tips: Finding Koshin-to
Hunting for Koshin-to adds a treasure-hunt element to any trip to Japan. Here is how to find them:
- Look at Crossroads: In ancient times, crossroads were considered spiritual boundaries where evil spirits could enter a village. Koshin-to were placed there to act as spiritual barriers.
- Explore Kamakura: The ancient capital of Kamakura is arguably the best place to see these stones. They line the hiking trails and nestle in the corners of temple grounds like Sugimoto-dera.
- Check Temple Entrances: Many Koshin stones were moved to Buddhist temples during road expansion projects in the 20th century.
- Etiquette: Treat these stones with respect. They are still considered sacred by locals. Do not climb on them or deface them. If you see coins or small offerings of rice or sake nearby, do not touch them.
Sources & Further Reading
To deepen your understanding of the cosmological systems that underpin the Koshin faith, looking into early Japanese historical records and Chinese Taoist texts is essential.
- The Baopuzi (Master Who Embraces Simplicity): A 4th-century Chinese text by Ge Hong, which details the concept of the Three Corpses.
- Nihon Shoki (The Chronicles of Japan): While primarily a history of the Imperial lineage and Shinto mythology, this text establishes the adoption of the Chinese sexagenary calendar system in Japan, which is the foundation of the Koshin timing.
- Local Folk Museums: If you visit areas like Kita-Kamakura or rural Saitama, local folk museums often house well-preserved examples and rubbings of these unique stones.
Next time you see a moss-covered stone with three monkeys by a Japanese roadside, you’ll know it’s not just art—it’s a monument to a community that once stayed up all night, battling supernatural worms to live a longer life.