Misuji

ミスジ is usually read as three lines, for the striations visible in a cross-section. It is cut from the infraspinatus, a muscle on the outer face of the shoulder blade, and it is one of the more heavily marbled small cuts on the animal.

The defining feature is a seam of connective tissue running down the centre of the muscle. In U.S. fabrication the same muscle is sold as top blade, and when it is cut across that seam it becomes a flat iron: the flat iron is specifically the top blade with the central sinew removed. That is the cleanest way to hold the relationship between the three names in your head.

Whether the sinew has been dealt with changes the cut completely. Left in and sliced thin across the grain, as yakiniku service usually does, it is unobtrusive and the marbling does the work. Left in and cooked as a thick steak, it is chewy in the middle in a way no amount of marbling fixes.

So the useful question to a seller is not only which muscle but how it has been fabricated. Thin-sliced misuji for a grill and a flat iron steak are the same muscle prepared on opposite sides of that decision, and yield differs between the two because removing the seam costs weight.

On a yakiniku menu, expect thin slices to grill quickly yourself. Follow the USDA guidance for whole beef steaks, 145F with a three-minute rest, and choose doneness to taste within that rather than judging by colour and elapsed time.

Exact yield and fabrication vary by seller, and misuji is a small cut, so portions are smaller than a loin steak by nature rather than by stinginess. As with every cut here, the grade quoted was read at a cross-section through the rib and describes the carcass rather than this particular muscle.

One more thing worth knowing before you compare prices. There are two of these on an animal, one per shoulder, and each yields a modest slab, so misuji is genuinely scarce in a way that a loin cut is not. Scarcity is a real reason for a price and it is not the same thing as quality, so treat it as an explanation of the number rather than a justification of it.