The Japanese fermented pickle made by burying vegetables in rice bran is nukazuke.
Nukazuke is produced by placing vegetables in a moist fermenting bed called nukadoko or nukamiso. The bed contains rice bran, salt, water, and often ingredients such as kombu, chili, ginger, garlic, sake, or fruit peels. Cucumbers, daikon, eggplant, carrots, and turnips are common choices.
Lactic-acid bacteria and yeasts in the living rice-bran mixture ferment the vegetables, producing a flavor that can range from pleasantly tangy to salty, sour, and pungent. Pickling time varies from several hours to several days, while longer fermentation creates a stronger taste. Traditionally, the bed is stirred daily to distribute moisture and oxygen and to discourage unwanted microbes.
Nukazuke is broader than takuan, which is specifically a pickled daikon preparation. Umeboshi uses salted and often dried plums, not a rice-bran bed. Tsukemono is the general Japanese term for pickled foods, so it is a category rather than the single technique described here.