Cut each slice of melting cheese into quarters. Slice the mentaiko open and remove the roe.

Cut the Sanma fillets in half.

Line a baking tray with aluminum foil and brush with olive oil. Arrange the Sanma pieces on the tray, top with mentaiko, and fold the cheese slices in half to layer them on top. Repeat to create 4 portions.

Sprinkle breadcrumbs over the portions and drizzle with olive oil. Cover with aluminum foil and bake in a toaster oven for about 8 minutes until the fish is cooked through.