Shell the eggs, cut in half lengthways and remove the yolks. Set the whites aside on a large plate.
Using a food processor, process the yolks with the mayonnaise and Wasabi powder until smooth. In a small bowl, gently mix the yolk mixture with the tobikko and pickled ginger. Add a little more mayonnaise if the mixture seems too dry.
Using a pastry bag or a spoon, fill the hollow of the egg white with the yolk mixture. Sprinkle the sliced scallions, white & black sesame seeds over the top. Garnish with additional tobikko, if desired.