Prepare the horse mackerel by filleting and marinating it in 4 tbsp vinegar and 1/2 tsp salt for 15 minutes.

Mix the freshly cooked rice with the sushi vinegar made from 2 tbsp vinegar, 2 tsp sugar, and 1/2 tsp salt.

Slice the myoga thinly and chop the shiso leaves finely.

Combine the marinated horse mackerel, seasoned rice, sliced myoga, chopped shiso leaves, and white sesame seeds in a large bowl.