Kūin-ji, Buddhist temple in Obama, Japan

Kūin-ji is a Sōtō Zen temple at the foot of Mount Ushirose in Obama, Fukui Prefecture. Its main hall enshrines a horse-headed Kannon, and the grounds contain the cave where the nun Yaobikuni is said to have entered eternal meditation. The temple also holds the graves of the Sakai lords of Obama Domain.

The site was the residence of the Wakasa shugo Takeda Motoaki, who built Noshima Castle in 1522; the present temple stands on that ground. After the Battle of Sekigahara, Kyōgoku Takatsugu became lord of Wakasa and took over the residence. His son Tadataka built Taiun-ji there as a memorial to him, but the Kyōgoku moved to Matsue in 1634. Sakai Tadakatsu then moved his father's remains here and founded the temple, renamed Kūin-ji in 1688 after his own posthumous name.

The temple is the family temple of the Sakai lords of Obama domain, and its name Kūin is the posthumous name of Sakai Tadakatsu. Its grounds hold the Sakai family graves, a city-designated historic site, and the cave where, by the temple's own origin account, the nun Yaobikuni entered meditation at the age of 800. The cave is a sea-eroded hollow in the slope of Mount Ushirose.

Kūin-ji stands in the Obama Otokoyama area of Obama, about 15 minutes on foot from JR Obama Station on the Obama Line, roughly 3 km from the Obama interchange and 2 km from the Nosoe junction on Route 27. The temple is the family temple of the Sakai lords of Obama, so the cemetery and cave are visited with restraint. The cave of the 800-year-old nun is a sea-eroded hollow at the foot of Mount Nosoe.

In the temple grounds stands a sea-eroded cave where, according to the temple's own origin account, the nun Yaobikuni entered eternal meditation at the age of 800; she is said to have been born in 654 and to have eaten mermaid flesh at sixteen, which kept her youthful. The cave is a city-designated historic site.