Kozen-ji, Buddhist temple in Tamba, Japan.

Kozen-ji is a Soto Zen temple on the site of a former fortified residence beneath Kuroi Castle. Its entrance is preceded by a roughly 80-metre moat called Shichikenbori and a high nozura-zumi stone wall, with a white plastered wall above. The main gate was moved here from Chigen-ji in Miyazu.

The temple began as Chikurin-zan Seigan-ji about 150 metres from its present site, and was burned when Naito Munekatsu of Yagi Castle attacked Kuroi Castle. Ogino Naomasa, lord of Kuroi Castle, rebuilt it. In 1626, fifty years after Kuroi Castle fell, the halls were moved onto the site of the castle's lower residence, and the temple became Soto Zen, named Kozen-ji, with Naomasa as founder.

The temple gardens embody traditional Zen principles, with stone arrangements and plantings creating spaces for contemplation. Visitors can see how nature is shaped as a tool for inner focus through careful artistic design.

Kozen-ji is about a 10-minute walk from JR Kuroi Station on the Fukuchiyama Line; by car, take the Maizuru-Wakasa Expressway to Kasuga IC, then Route 175. The precinct is entered through the romon gate, with the roughly 80-metre Nana-ken-bori moat and the stone walls in front of it. The moat and high stone walls are part of the Kuroi Castle Site, a national historic site.

The temple's moat, the Shichikenbori, runs about 80 metres along a stone wall roughly 5 metres high, built in the nozurazumi style also seen at nearby Kuroi Castle; part of the wall uses kirikomi-hagi stonework, thought to be a later repair. The moat and wall are believed to reuse the lower residence of Kuroi Castle as they stood.