Saikō-ji, Buddhist temple in Tonoshō, Kagawa Prefecture, Japan

Saikō-ji is a Buddhist temple of the Kōyasan Shingon school in Tonosho on Shōdoshima, with the mountain name Ōjisan and the cloister name Rengein. Its main hall was built in 1933 in the Momoyama style, and a three-storey pagoda named the Tower of Vows, of Japanese style in wood with tiled roofing, was added in 1975. The temple grounds also hold a bell gate with a plaque reading "Shishi", a reception hall and an inner sanctuary.

The temple serves as the 58th stop along the Shōdoshima Pilgrimage route and features a pagoda known as the Seikou-ji Okunoin Oath Tower. This location marks an important station on a pilgrimage path that has guided travelers and worshippers for centuries.

Around the temple stand structures from the Meiji period, including former storehouses for kimonos, soy sauce producers, and printshops. These buildings show what daily work and trade looked like in this neighborhood long ago.

The temple grounds are open to visitors and offer free parking along with easy access to nearby galleries and shops. The narrow alleyways surrounding the site are best explored on foot, and there are plenty of places to stop and look around.

The temple's former okunoin, the Nangō-an, is now the Ozaki Hōsai Memorial Museum, marking where the Meiji-era haiku poet spent his final days. The grounds also hold a ginkgo over 250 years old, with a trunk circumference of 3.6 m and a height of 18 m, designated a town natural monument in 1933.