This is a National Treasure Medal "Chuson-ji" issued by the Japan Mint. Made of pure silver, approximately 160g, and stored at home. There is some tape residue on the edge of the case that holds the outer box with "Chuson-ji" printed on it (see the last photo). The photo of the back side appears yellowish, but this is likely due to the difference in surface treatment of the medal affecting the photo (the actual color is metallic).