The Japanese clam is usually processed fresh, although the mussel meat can also be bought frozen without the shells. The most common and probably also the most famous dish for which it is used is the "Spaghetti Vongole".
The mussels are usually commercially available in 1kg nets. Since fresh mussels are still alive, they should be stored in the fridge and only for a short time.
One technique to clean the mussels before use is:
Make a salt solution with 1l of cold water and 32g of sea salt and place the mussels in it loosely. The salt concentration is . . .