Beat the eggs with sugar and salt. Cook in a tamagoyaki pan, rolling the egg into layers, then slide out and cut into 4 slices.
Slice the Spam into 4 even slices about 1cm thick. Pan-fry in a dry pan over medium heat for 2–3 minutes per side until golden. Reserve the empty can.
Wash the empty Spam can. Line with plastic wrap. Pack lightly with warm rice — about 1/4 to 1/3 of the can height. Lift out using the wrap. Repeat to make 4 rice blocks.
On a fresh sheet of plastic wrap, lay a strip of nori, then a rice block on top. Pipe a squiggle of Kewpie mayo on the rice. Top with a slice of tamagoyaki, then a slice of fried Spam.
Wrap the nori around the Spam, then tighten the plastic wrap around the whole onigiri. Let rest for 1–2 minutes, then unwrap and serve.
