The Yamagata Beef Sando (山形牛サンド) is sandwich with Yamagata beef (premium wagyu region).
It sits within the Japanese Sandos family of French sandwiches — specifically the The Wagyu & Regional Beef Sando cluster, which gathers the regional and stylistic variants that share its frame.
For the broader The Wagyu & Regional Beef Sando tradition that frames this sandwich, see The Wagyu & Regional Beef Sando.