Actually had this last night at Tomo (http://www.tomorestaurant.com/) here in Atlanta. It was lightly fried and quite tasty. This is the second time that I’ve had it.
Had this a couple months ago here in a local sushi joint. Sushi chef barely speaks English and my wife and I both heard Cuttlefish. I was commenting that I had cuttlefish and we probably misheard. I finally asked the waiter and he said, “Shirako”. He hesitated and finally said, “It’s Cod Sperm.”
Tasted like a brain. Interesting to try and at least it speaks to the quality of the restaurant.