You might recognized today’s yokai from his brief appearance in my Kickstarter video, where I referred to him tongue-in-cheek as “the original Master Splinter.” However, there is nothing tongue-in-cheek or silly about the true story behind this yokai. It’s a tale of trust, betrayal, and ultimate revenge (and would it be a Japanese ghost story with revenge?).
Tesso (鉄鼠, てっそ)
Tesso wasn’t born a yokai. In fact, he was a real person. Long ago, during the time of Emperor Shirakawa (reigned 1073-1087), there lived a man named Raigō. Raigō was the abbot of Mii-dera, a monastery in Shiga prefecture at the foot of Mount Hiei.
The history of this period was all very complex, with conflicting power bases, rival emperors, family rivalries and so on (if you are looking for a great primer on Japanese history, I would suggest The Mikado’s Empire by W.E. Griffis), so I won’t go into detail, but suffice it to say, the Emperor was desperate for a proper male heir.
Emperor Shirakawa approached Raigō and asked him to pray for a son to be born. Raigō prayed long and hard, and sure enough in 1074 a son, Prince Taruhito, was born. The Emperor promised to give Raigō anything he wished, and so in return for his prayers, the abbot asked that a splendid new building be built at Mii-dera so he could train new priests there. The Emperor gladly agreed… but as I said this was a time of conflicting power bases, and Mii-dera had a rival: Enryaku-ji temple, on top of Mt. Hiei, wielded great political power as well as having a powerful army of warrior monks at its disposal. Bowing to pressure from Enryaku-ji, the Emperor reneged on his promise to Raigō.
Raigō began a hunger strike in protest of Emperor Shirakawa’s broken promise, but the Emperor would not — or could not, rather — go against Enryaku-ji’s power. On the 100th day of his hunger strike, Raigō passed away, full of rage towards the unfaithful Emperor and the rival monastery of Enryaku-ji.
What happens next is where the true story takes a turn for the bizarre, and where different books range wildly in their accounts. Shortly after Raigō’s death, a ghostly vision of the abbot was seen hovering near young Prince Taruhito’s bed. So great was the grudge of Raigō that, upon his death, he was able to turn himself into an onryō, a ghost driven by pure vengeance. Shortly afterwards, the young prince died, leaving the Emperor heir-less once again.
Raigō did not come back as an ordinary ghost (if such a thing can be said to exist in Japanese folklore…). Instead, he used black magic to turn himself into a gigantic rat. His body was said to be as hard as stone and his teeth and claws as strong as iron, earning him the nickname Tesso, or “the iron rat.” Tesso summoned a massive army of rats, which poured through Kyoto and up Mt. Hiei, until they arrived at Enryaku-ji. There, Tesso wreaked his vengeance. The army of rats poured through the monastery complex. They chewed through the walls and doors, crawled into the roofs, and chased away the monks. They devoured the precious sutras, scrolls, and books of the temple, eating and despoiling everything they found. They even ate through the precious statues of the Buddha.
Nothing could stop Tesso and his army of rats until finally a shrine was built at Mii-dera to appease his vengeance. Raigō’s spirit is still enshrined there, and you can visit it today. One interesting footnote to the story: while Buddhist buildings are typically built facing the east, Raigo’s shrine is built facing the north; it points up Mt. Hiei, directly at Enryaku-ji.
OMG, why haven’t you backed my Kickstarter project yet?? This and other great illustrated yokai tales could be in your hands in glorious paperback or hardcover, postcards, and fine art prints, if only you pledge to back the project before October 31st!






