Make the 5-ingredient sushi, and mix it into 1/2 of the sushi rice. Mix in the sakura denbu to the other half of the sushi rice. Blanch the spinach briefly, and cut into 3 cm pieces. (Here's the recipe for 5-ingredient sushi: https://cookpad.com/en/recipes/153151-5-ingredient-chirashi-sushi)
https://cookpad.com/us/recipes/153151-5-ingredient-chirashi-sushi