Category: Kai (shellfish). Season: October to February.
Once found in Tokyo Bay, giant clam has become very scarce, so it is often substituted with geoduck. In either case, the portion of the shellfish used for nigiri is the outside "siphon" that extends out of the shell. Served with nikiri and wasabi, mirugai is toothy, firm and crunchy in texture, with a sweet, delicate sea flavor and hints of seaweed.