Preheat oven to 380°F (190°C).
In a large bowl, mix the 4 cups of cooked sushi rice with 3 tbsp rice vinegar. Press the seasoned rice evenly into the bottom of a 9x13 inch baking dish.
Sprinkle half of the 1/4 cup of furikake seasoning evenly over the pressed rice layer.
In a separate bowl, combine 16 oz shredded imitation crab, 8 oz softened cream cheese, 1/2 cup Kewpie mayonnaise, and 2 tbsp Sriracha until well mixed.
Spread the spicy crab mixture evenly over the rice layer in the baking dish.
Bake in the preheated oven for 15-20 minutes, or until the top is bubbly and lightly golden.
Remove from the oven. Drizzle with 2 tbsp unagi sauce and sprinkle the remaining furikake and 1/4 cup chopped green onions on top.
Serve warm by scooping onto individual roasted nori sheets.