| Prince Nagaya | |
| Birth Date: | 684 |
| Death Place: | Nara, Japan |
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| Father: | Prince Takechi |
| Mother: | Princess Minabe |
Nagaya (Japanese: 長屋王 ) (684 – 20 March 729) was a politician of the Nara period and an imperial prince of Japan, a son of Prince Takechi (grandson of Emperor Tenmu).
His father was Prince Takechi and his mother Princess Minabe (a daughter of Emperor Tenji and Empress Genmei's sister). He married Princess Kibi (his cousin, a daughter of Empress Genmei and Empress Genshō's sister).
He was substantially influential in politics owing to his membership of the Imperial family of the most noble birth, and there were no other competitive Imperial members at that time. A large residence was allocated to him in a prestigious part of Heijō-kyō.
The Fujiwara clan were the most powerful competitors of Nagaya. Fujiwara no Fuhito, the leader of the house, had been the most powerful courtier in the court in the days when Japan was under the reign of Empress Genshō, a cousin of Nagaya's. After Fuhito's death in 720, Nagaya seized complete power within the court. This power shift was the source of later conflicts between him and Fuhito's four sons (Muchimaro, Fusasaki, Maro and Umakai) in the reign of Emperor Shōmu.
In 729, the four sons charged him with a false crime and Nagaya received the death penalty. He was forced to commit suicide. His wife, Princess Kibi, and his children were killed at the same time.
Parents
Consorts and issue
Imperial Princess Kibi (吉備内親王, 686–729), Prince Kusakabe's daughter
Lady Ishikawa (石川夫人), daughter of Ishikawa no Mushina (石川虫名)
Fujiwara no Nagako (藤原長娥子), daughter of Fujiwara no Fuhito (藤原不比等)
It is said that, as Prince Nagaya was forced to die unreasonably, he bore a grudge against the living after his death. The following are believed to have been the victims of Nagaya's curse:
Muchimaro, Fusasaki, Maro and Umakai, responsible for the prince's death, caught smallpox one after another and eventually all of them died during a major Japanese smallpox epidemic in 737.