Japanese Kakuni and Buta no Kakuni: Pork Belly Braising and the Nagasaki Connection

Kakuni (角煮 — square simmered) is Japan's approach to the long-braised pork belly: thick cubes of skin-on pork belly simmered in a soy-mirin-sake-dashi mixture over several hours until the collagen in the skin and connective tissue has fully dissolved into gelatin, the fat has rendered to silky tenderness, and the thick sauce has reduced to a lacquer that coats every surface. The dish's origins in Japan trace directly to the Chinese community that settled in Nagasaki (China's primary gateway to Japan) — the Chinese red-braised pork belly (hong shao rou) travelled through Nagasaki and was adapted through Japanese seasoning principles (more dashi, less spice, more mirin sweetness). The Nagasaki version (Nagasaki kakuni) remains distinctive: larger blocks than the standard preparation, often accompanied by steamed bread buns for wrapping (an explicitly Chinese presentation), and served at the traditional Shippoku banquets that blend Chinese, Dutch, and Japanese food cultures. The Okinawan parallel — Rafute — uses the same pork belly preparation but cooked in awamori (Okinawan spirit) and soy with abundant sweetness, reflecting the separate Chinese influence on Okinawan cuisine distinct from Nagasaki. The technique principle is the same across all versions: preliminary blanching to remove impurities, initial browning (sometimes), then long gentle braising in seasoned liquid with multiple reduction stages. The finished kakuni should be: deep mahogany in colour, trembling-tender when pressed gently, lacquered with reduced sauce, with the skin gelatinised to transparency. Karashi mustard or shichimi at service cuts the richness.