Preheat the oven to 400°F (200°C).
In a small bowl, whisk together rice vinegar, sugar, and salt until dissolved. Fold this mixture into the warm cooked sushi rice.
Press the seasoned rice firmly into an even layer at the bottom of a 9x13 inch baking dish.
Sprinkle 1.5 tablespoons of Furikake evenly over the rice layer.
In a large mixing bowl, combine the flaked salmon, shredded imitation crab, Japanese mayonnaise, sriracha, and softened cream cheese. Mix until the components are fully incorporated.
Spread the salmon and crab mixture evenly over the rice layer in the baking dish.
Bake for 15 to 20 minutes, or until the top is heated through and begins to lightly brown.
Remove from the oven and drizzle with Unagi sauce. Sprinkle with the remaining Furikake and sliced green onions.
Serve immediately by scooping portions into small squares of roasted seaweed (nori).