The name has nothing to do with England. It is a slurring of igisu, the name of the seaweed it is made from, and the coincidence has been confusing outsiders for a long time.

Dried igisu is simmered until it dissolves. Cooked ingredients, boiled or fried, are stirred through it, and the mixture is poured into a mold and left to set. Cut through it and the cross-section shows everything suspended inside where it stopped, in the way that a terrine does.

The history is a displacement. After the Shimabara rebellion, the shogunate repopulated the depopulated peninsula by moving farmers here from domains across Shikoku. Those settlers found that igisu grew in the Ariake Sea just as it had in the Inland Sea they came from, and started making the dish they already knew.

It was daily food here for a very long time, made without ceremony. Now the seaweed itself has become an expensive ingredient and the preparation takes real work, so the dish has been drifting toward being something that appears only at weddings and funerals. What it records, underneath all that, is a group of people arriving somewhere they had not chosen and finding one familiar thing growing in the water.