Condition: Generally in good condition. The resin has yellowing due to aging, minor scuff marks on the surface, and some scratches and dent marks along the edges. This work is done by pouring resin into an acrylic case, in which naphthalene key objects are placed. The concept of this work is that the objects gradually disappear over time, utilizing the properties of naphthalene, which evaporates when exposed to air. For this reason, small holes are thought to be made in the three keys close to the resin surface, where part of the naphthalene in contact with air has oxidized and turned yellow. An acrylic plate is thought to be accompanied with this work to prevent exposure to air.