A depachika katsu sando is the cutlet sandwich carried out of a department-store food hall, and the address is the point. A plain katsu sando is a fried cutlet on shokupan with tonkatsu sauce; this one is that sandwich from a counter that often belongs to a named tonkatsu restaurant, boxed under the restaurant's reputation and priced accordingly. What defines it is the standard the basement enforces: a cutlet good enough to stand behind a known name, bread and sauce calibrated to that cutlet, and a cut clean enough to photograph through the lid. The cutlet, the bread, and the sauce need each other here more than usual, because at this price a single weak component is the thing the customer notices first.
The craft is the depachika standard applied to fried pork. The cutlet is a graded loin or fillet, pounded even, coated in coarse panko, and fried so the crust goes deep gold and stays crisp while the meat holds its juice rather than drying to a plank. It is rested and sliced so the cross section shows an even band of pink-edged pork inside an unbroken crust. The shokupan is fresh and fine-crumbed, crustless when the house cuts it that way, often spread thin with butter or mustard to seal it against the sauce. The tonkatsu sauce is laid on with control, sweet and tangy and enough to season every bite without soaking the crust soft before the box is opened. A good one keeps a faint crackle against soft bread and reads as a restaurant cutlet that happens to be in bread. A poor one is a thin dry slab, under-sauced so it tastes of bread, or fried far enough ahead that the panko has gone oily and limp, the exact failure a named counter cannot afford.
The variations follow the restaurants and the cut. A famous tonkatsu house may box a thick premium loin; another leans on a leaner fillet; some counters run a beef or ebi cutlet under the same premium logic. Convenience-store and station katsu sando chase the same outline at a lower grade, a different sandwich at a different price, and each deserves its own article rather than being crowded in here.