海向寺, Buddhist temple in Sakata, Japan

Kaiko-ji is a Buddhist temple in Sakata, a port city on the Japan Sea coast in Yamagata Prefecture. It consists of a main hall, a gate, and several smaller structures arranged around an open courtyard.

The temple is affiliated with the Shingon school of Buddhism and has long been connected to the Dewa Sanzan, the three sacred mountains of the Tohoku region. It served as a base for pilgrims traveling to those mountains over the centuries.

Kaiko-ji holds two sokushinbutsu, the mummified bodies of the monks Chukai Shonin and Enmyo Kai Shonin, kept on display in the temple. Of the sixteen such mummies in Tohoku, eight are in Yamagata Prefecture and six in the Shonai region. The temple belongs to the Chisan branch of Shingon Buddhism.

Shoes should be removed before entering the main buildings, and visitors are expected to keep their voices low during prayer times. The paths across the grounds are easy to follow and accessible on foot.

The temple is home to several mummified monks known as sokushinbutsu, individuals who followed an extreme form of ascetic practice intended to mummify the body from within. This rare phenomenon is found almost exclusively in the Tohoku region of Japan.