Preheat the oven to 400 degrees Fahrenheit (200 degrees Celsius) and line a baking sheet with parchment paper.
Pat the salmon fillets dry with paper towels to ensure the glaze adheres properly.
Arrange the salmon fillets on the prepared baking sheet with skin-side down.
In a small bowl, whisk together the Japanese mayonnaise, unagi sauce, and wasabi paste until smooth.
Spread the mayonnaise mixture evenly over the top of each salmon fillet.
Generously sprinkle the furikake seasoning over the glaze on each fillet, pressing lightly to secure the seeds and seaweed.
Bake in the center of the oven for 12 to 15 minutes, or until the internal temperature reaches 145 degrees Fahrenheit and the fish flakes easily.
Remove from the oven and garnish with sliced green onions before serving.