In Japan the Philly cheesesteak is a specialty-shop import, the American classic rebuilt with the care a Japanese kitchen tends to bring to a borrowed dish. The target is the genuine article: thin-shaved beef griddled hot, soft onions, and melted cheese packed into a long soft roll. Japanese versions are not trying to reinvent it; they are trying to get it right, which usually means a kitchen that has studied what the sandwich is supposed to feel like in the hand and on the griddle rather than treating it as a generic steak sub. The result is recognizably a cheesesteak, with the messy, beefy, cheese-bound character intact, executed with the consistency and ingredient discipline that defines this kind of specialty operation in Japan.
The craft lives on the griddle and in the bind. The beef is sliced very thin and cooked fast and hot so it stays tender, chopped on the flat-top as it cooks and folded together with onions softened in the same beef fat. The cheese is the binding agent, whether a processed melt for the gooey style or provolone for a sharper one, and it has to be worked into the meat while everything is still hot so the filling holds as one mass instead of sliding out in pieces. The roll matters as much as the filling: soft enough to compress to the meat, sturdy enough to take the grease without collapsing, lightly toasted on the cut faces. A good one is hot, savory, and cohesive, the cheese threading through the beef. A sloppy one is greasy and loose, the meat overcooked to chew, the roll either too crusty to bite cleanly or so soft it disintegrates halfway through.
Within the imported category there is real spread. Some shops follow the gooey processed-cheese school; others go provolone, and a few add bell peppers or mushrooms for a loaded build. There are leaner Japanese adaptations that dial back the grease for local palates, and richer ones that lean into it as a heavy, indulgent lunch. The broader story of American sandwiches naturalized at Japanese specialty shops, from the Reuben to the New Orleans po'boy, is its own large subject and deserves its own article rather than being crowded in here.