これだ
日本人だけの数か

https://www.nikkei.com/article/DGXMZO40732110R30C19A1L82000/
https://article-image-ix.nikkei.com/https%3A%2F%2Fimgix-proxy.n8s.jp%2FDSXMZO4073604031012019L82001-1.jpg