Tsukudani is thinly sliced seafood, meat or seaweed that has been simmered in soy sauce and mirin. As a flavorful accompaniment to plain rice, tsukudani is made salty enough to not go bad, allowing high osmotic pressure to preserve the ingredients from microbial spoilage similarly to other types of pickles. Its name originates from Tsukudajima, the island where it was first made in the Edo period. Many kinds of tsukudani are sold, and common ingredients include kelp, short-neck clam, young lancefish, and nori. Traditionally made tsukudani is preservable and has been favored as a storable side dish in Japanese kitchens since the Edo period.