Amaebi is "nanban" ebi in Niigata. "Nanban" usually references Portuguese-derived foods that are fried or otherwise unconventionally prepared (by 1500s Japanese standards) but I'm really not sure how a local shrimp got this designation. It is always served as nigiri, with the added bonus at this meal of its roe appearing as a topping for torafugu shirako over a spoonful of the sushi rice.