Sayuri was a favored concubine of Sassa Narimasa, said to be a peerless beauty, whom he brutally tortured and killed on suspicion of infidelity.

The story goes that Narimasa fell in love with Sayuri at first sight and made her his concubine. He lavished affection on her, and was overjoyed when she became pregnant in 1584. His other three concubines were jealous of Sayuri, and when Narimasa left Ecchuu on a trip to meet with Tokugawa Ieyasu in December of that year, spread the rumor that she was in secret communication with one of Narimasa's vassals, a man who had stayed behind at Toyama Castle because of illness, Takezawa Kumashirou (sp?) (竹沢熊四郎). They claimed that the child belonged to Kumashirou, not Narimasa.

Narimasa dismissed the rumors at first, but found a small brocade sachet at the door of Sayuri's bedroom which belonged to Kumashirou (said to have been placed there by the other concubines). He flew into rage and put Kumashirou to the sword on the spot. He then hanged Sayuri by her feet to a tree in the Jintsuu River Basin and slowly cut her to pieces. He also beheaded the 18 members of her family and crucified their bodies at the prison gates.

The scene is described in the Taikouki: at the moment of her death, Sayuri, her lips bitten through, bloody tears flowing down a once-beautiful face now twisted into a malevolent mask, cursed Narimasa: "As Narimasa beheads me here, my enmity shall a demon become, to grow year by year until I have killed all thine issue even unto the extinction of thy family name." Those watching covered their eyes, and those who heard felt their hair rise at those words.

Stories say that a drifting fire would appear on stormy nights at the spot where Sayuri died, and sometimes a freshly-severed head with wild hair waving in the air saying "Sayuri, Sayuri." The fire was called "Sayuri Fire". The story goes that Sayuri became a vengeful ghost whose curse later killed Sassa Narimasa (though not his children). Sightings of the fire occurred as late as the Meiji Era.

The hackberry tree from which Sayuri was said to have been hanged was burned during the air-raid of Toyama City in World War II. Two second-generation hackberry trees now stand on the spot.