Ryuko (March 20, 1649 - July 26, 1724) was a Buddhist priest of the Shingi Shingonshu sect (new Shingonshu sect of Buddhism) who lived in the mid-Edo period. He came from an old family, the Kawabe clan of Yamato Province. He was first named KAWABE no Takanaga, and his azana (courtesy name) was Eishun.
In 1658 he entered the Buddhist priesthood and was trained at Hase-dera Temple and Toshodai-ji Temple, thereafter acquiring Esoteric Buddhism at Daigo-ji Temple in Nara and studying Confucianism and the thought of Laozi and Zhuangzi. In 1686, under the command of Tsunayoshi TOKUGAWA who was the 5th Seii Taishogun (literally, the great general who subdues the barbarians), Ryuko became Jushoku (a head priest) of Chisoku-in Temple of Mt. Tsukuba which was in charge of incantation and prayer for the shogun's family, thereby rapidly winning devotion from Tsunayoshi. In 1688 Chisoku-in Temple was transferred to the outside of Kanda-bashi Bridge and was renamed as Goji-in Temple, a kaisan (a founder of temple as the first chief priest) of which was Ryuko. In 1695, he became the first Daisojo (a Buddhist priest of the highest order) among the priests of the Shingi Shingonshu sect.
However, he was ousted upon the death of Tsunayoshi. Ryuko was banned from visiting the Edo-jo Castle in 1709, and his request for a return to the Chisoku-in Temple of Mt. Tsukuba was turned down, and he thus returned to his hometown Yamato, where he died in despair. There are two tombs of Ryuko in existence, one is in Taishi-cho, Minamikawachi County, Osaka Prefecture, and the other is behind Nara municipal Saki Kindergarten.
He was favored by Tsunayoshi and his biological mother Keishoin and allegedly recommended the issue of Shorui-Awaremi-no-rei (ordinances of animal protection), but this is denied today on the grounds that Ryuko had not yet been in Edo at that time. However, it was Ryuko who recommended Tsunayoshi and Keishoin to rebuild temples and shrines of Kyoto and Nara, which surely played a part in the financial deterioration of the shogunate as a result.