Ryūkoku-ji, Buddhist temple in Toyooka, Japan

Ryūkoku-ji is a Buddhist temple featuring wooden buildings with tatami mat flooring set among farmland and green spaces in Hyogo Prefecture. The connected structures allow different religious activities to happen throughout the grounds.

Founded in the Muromachi period as the family temple of Kakiya Takakuni, head of the four Yamana generals; the actual founder is also said to be his relative Kakiya Mitsunari. In 1576 Mitsunari received a peony brought from Ming China by the monk Sakugen Shūryō, which began the temple's peony cultivation. In 1623 the temple moved from Ase Valley to its present site.

The temple belongs to the Sōtō school, not Rinzai. Its name comes from Kakiya Takakuni, whose family founded it as his family temple. Peonies brought from Ming China by the monk Sakugen Shūryō were given to Kakiya Mitsunari in 1576, starting the cultivation that earned Ryūkoku-ji the name "Peony Temple".

The temple lies in the Arakawa district of Hidaka, Toyooka; from JR San'in Line Ebara Station take a bus toward Kannabe Kogen and get off at Uemura Boken-mae, then walk about 20 minutes, or take the Inaka-sanpo line to Mikata Community Center and walk about 5 minutes. By car, leave National Route 482 at the Ibu intersection for Prefectural Route 259, or turn onto Route 268 near Nishi Junior High; the temple is beside Mikata Elementary School.

The temple's peonies trace back to 1576, when the Zen master Sakugen Shūryō gave Kakiya Mitsunari a peony he had brought back from Ming China, along with a certificate of the dharma name Etsugan. The garden was rebuilt by local people saved from famine with rice from the temple storehouse during the Tenpō era (1831–1845).