The menu is collecting tube of fish Shirako semen or fish called sperm of fish bag.
Shirako means white children or innocent children.
This menu is very commonly eaten in winter
Shirako a menu of the Japanese. Choose to eat only certain types of fish. For the fish that prefer to eat this bag sperm have both cod fish and puffer fish.
Eat both cooked or just catch some fish on the boat, they can eat fresh fish filet, depending on individual tastes.
They say within the bag collect semen is crammed with sperm, especially to eat fresh will feel soft and tough juicy. It is similar to the taste of fresh cream custard soft tongue.