In Japan the corn dog goes by amerikan doggu, the American Dog, and it is festival food before it is anything else: a hot dog skewered on a stick, dropped in batter, deep-fried to a deep gold, and handed over hot at a matsuri stall, a convenience store warmer, or a school fair. The stick is the whole delivery system, a handle that lets you eat it walking through a crowd without a plate or a wrapper to manage. It earns its place in a sandwich catalog the way a hot dog does, an enclosed protein in a bread casing, just here the bread is a fried batter shell formed around the sausage rather than a split bun beside it.
The technique is simple and unforgiving. The sausage is patted dry and often given a thin dusting so the batter grips it instead of sliding off in the oil. The batter is the local signature: where the American version leans on a coarse, distinctly cornmeal coating, the Japanese reading is typically softer and more cake-like, closer to a sweet wheat-flour batter, sometimes barely corn-forward at all, which gives a fluffier, slightly sweet jacket rather than a gritty crust. It is dipped, the excess shaken off, and fried until the shell is even and crisp and the sausage is heated through. A good one has a thin, sealed, golden coat with a tender interior crumb, a sausage that is hot and juicy and centered on the stick, and a shell that crackles without being greasy. A sloppy one is pale and oil-logged, the batter cracked and weeping fat, the sausage cold in the middle or sliding off the skewer because nothing helped the coating hold.
The variations are mostly about what you put on it and what is inside. The convenience-store standard comes plain or with a stripe of ketchup and yellow mustard; festival stalls sometimes offer a sugar dusting, which sounds odd and works because the batter already leans sweet. Cheese-filled versions tuck a core of melting cheese alongside the sausage; smaller two-bite editions show up in lunchboxes and kids' menus. Variants swap the frankfurter for a fish-sausage or a chikuwa core, and once you fold cheese in and reshape it the thing drifts toward the wider sozai pan savory-bread family, which deserves its own article rather than being crowded in here.