This flat and shallow miniature shrine (zushi) is outfitted with hanging gilt bronze fittings on its exterior. When opened, there is a central panel that can be removed; its front has a circular bronze sheet with an inner circle enshrining relics. The Diamond World (Skt. Vajradhātu; J. Kongōkai) mandala is painted on its reverse. The back wall of the shrine, facing this mandala when the panel is inserted, has the Womb World (Skt. Garbhadhātu; J. Taizōkai) mandala, and the doors have paintings of two Wisdom Kings: Fudō Myōō (Skt. Acala) and Gōzane Myōō (Skt. Trailokyavijaya). The shrine comes from Kakuanji Temple in Nara.
 
NAITO SakaeEnglish by Mary Lewine 
Buddhist Art Paradise: Jewels of the Nara National Museum. Nara National Museum, 2021.7, p.331, no.219. 

This rather flat feretory can be hung around the neck if a braid is attached to a pair of fittings at its top, but judging from the holes in the bottom plate, it is conceivable that a platform had once been attached to this feretory for Buddhist services.
A partition panel is placed within the feretory onto which a round mirror is attached. Radiating lines drawn on the panel indicate the light rays which are supposed to be sent out from the holy mirror. The center of the mirror is scooped out to provide room for inserting a container for relics and a gilt-bronze holy letter. On the reverse side of the panel, the Kongō-kai (Vajradhātu) Shuji (Sanskrit symbols) Mandala is painted, and inside the Taizō-kai (Garbhadhātu) Shuji Mandala painted on a silk fabric is attached onto the back wall of the feretory, so that the two mandala paintings representing two realms face each other. Fudo-myō'ō (Acalanātha) and Gozanze-myō'ō (Trailokyavijaya) are painted on the reverse side of the double door of the feretory. It is notable that both of the myō'ō images reflect the idea of esoteric Buddhism.
The inscription about how this feretory for forty-five relic pieces was made and the date of production (1387) is written in ink on a paper strip which is attached to the hole of the partition panel, where the relic container is to be inserted. The paper strip is surrounded by four holy letters written on the panel which represent four Buddhist saints of the Kongō-kai. This feretory used to be kept in Gakuan-ji temple in Nara. 
Masterpieces of Nara National Museum. Nara National Museum, 1993, p.109, no.85.