Saikoji Temple in Naka-ogi is mentioned in the diary of Kujo Masamoto, the lord of Hinenosho, when he stayed in the Iriyamada Village of Hinenosho. Its Yakushi-do hall still remains, and while its roof was originally covered with tiles, they were replaced with copper plates during repair of the roof in 1984. A munafuda dated 1401 was found in the attic during the repair work. Based on it, as well as the style of the roof tiles, it is estimated that the hall was constructed around that year.

The three images are enshrined in a miniature shrine on a shumidan in the hall. A different technique was applied to each of the three images. The yosegi-zukuri technique was used for the principal image, while ichiboku-warihagi-zukuri (a technique for creating a statue by splitting and joining pieces of wood) was adopted for Nikko Bosatsu, one of the two attendants, and ichiboku-zukuri (a technique for creating a statue from a single block of wood) was adopted for Gekko Bosatsu, the other one. The principal image represents the characteristics of the Fujiwara carving style, such as the soft features of the face, gentle and slight physique and well-arranged expressions of the texture of cloth. An ink-penned inscription on the back of the base of Nikko Bosatsu indicates that it was presented in 1145, and the images are estimated to have been created around that time. The optative sentence written on the wooden board that runs through the center of the base of the principal image is very rare because no other statues from that period have such a sentence.