Make rice over stovetop or in a rice cooker. Set aside and keep warm
Mix sugar, soy sauce and mirin in a small bowl until sugar has dissolved. Set aside.
Heat approximately ½ tbsp of oil in a frying pan. Pan fry Spam slices until browned on both sides.
Brush sauce mixture on both sides of the Spam and continue to fry until slightly caramelized. Remove from pan and set aside.
Wash and dry the Spam can. Line the inside with plastic wrap. Pack rice into the can so it’s about ⅓” thick.
If you’re using kimchi, place a layer of kimchi on top of the rice.
Place a slice of the fried Spam on top of the kimchi. Gather the excess plastic wrap around the top of the Spam and continue to pack down. Pull out the musubi and set aside. Repeat with the remaining slices of Spam.
Lay down a strip of nori on your work surface. Unwrap a Spam and rice block and center it on top of nori. Fold the nori tightly around the musubi and seal with a dab of water.
Repeat with remaining musubis and enjoy!