"Demon Core is a nickname given to a spherical core that was experimented on as a part of the Manhattan Project. The core was involved in two fatal incidents in 1945 and 1946, with one of the incidents caused by severe safety protocol violations as a physicist let a screwdriver, with which a beryllium hemisphere was held, slip. Starting in 2018, the incident gained popularity as a historic reference, particularly among Japanese artists, inspiring memes and fan art of anime girls experimenting with the core."