Zenkō-ji is a Buddhist temple located in Nagano, Japan. The temple was built in the 7th century. Nagano City, established in 1897, was originally a town built around the temple. Historically, Zenkō-ji is perhaps most famous for its involvement in the battles between Uesugi Kenshin and Takeda Shingen in the 16th century, when it served as one of Kenshin's bases of operations. Currently, Zenkō-ji is one of the last few remaining pilgrimage sites in Japan.
Zenkō-ji was founded before Buddhism in Japan was split into several different sects, so it currently belongs to both the Tendai and Jōdoshū schools of Buddhism, and is co-managed by twenty-five priests from the former school, and fourteen from the latter. The temple enshrines images of the Amida Buddha. According to legend, the image, having caused dispute between two clans, was dumped into a canal. It was later rescued by Yoshimitsu Honda. The temple was thus named "Zenkō," according to the Chinese transliteration of Yoshimitsu's name.
The temple contains a statue of Binzuru, a physician who was said to be Buddha's follower. Visitors to the temple touch the statue in order to cure their ailments. The temple also contains an inner prayer chamber, accessible to visitors. Currently, a daily morning ritual is held there by the high priest or priestess. From the inner chamber, a narrow staircase leads down to a completely dark corridor. In this corridor worshippers try to touch a metal key hanging on the wall, in order to gain enlightenment. The key represents the Key to the Western Paradise of the Amida Buddha.