The main hall of Kai Zenkoji is one of the largest wooden structures in eastern Japan, measuring approximately 38m east-west, 23m north-south, and 26m high. The temple gate, called Sanmon, is about 20m high, about 15m wide, and about 10m deep, which is also the largest in eastern Japan.

Kai Zenkoji Temple is also known as a temple related to Takeda Shingen. In the main hall, "Zenkoji Nyorai Mikage", which is said to have been dedicated by Shingen Takeda, is enshrined. Also, in front of the temple gate, there is a statue of Shingen Takeda on horseback.