Rinse the rice in a fine-mesh strainer under cool running water, scrubbing with your fingers until the water runs clear, about 1 minute. Drain well, then add the rice and water to a medium saucepan. Bring to a boil over medium-high heat. Cover, reduce the heat to low, and simmer until the water is absorbed, about 15 minutes. Turn off the heat and keep covered to steam. Meanwhile, prepare the Spam.

Slice the Spam lengthwise into 8 pieces to create rounded rectangular pieces, about ⅜" thick.

In a small bowl, whisk together the soy sauce, brown sugar, mirin, rice vinegar, and sesame oil. Set aside.

Heat the vegetable oil in a large nonstick pan or frying pan over medium heat. Add the slices to the pan in a single layer and fry until golden brown, about 2 to 3 minutes per side.

Reduce the heat to low and pour the glaze into the pan. Flip the Spam slices to evenly coat both sides, then simmer until the sauce slightly thickens and clings to the meat, about 1 to 2 minutes per side. Do not overheat the sauce or it will burn. Transfer the pieces to a plate.

Cut the nori sheets into 4 strips, about 2-inches wide to expose the meat and rice for a nice presentation. You can also cut them wider for a fully wrapped musubi, especially if you enjoy more seaweed flavor.

Make one musubi at a time. Lay a strip of nori, rough side up, on a clean cutting board. Place the musubi mold in the center, positioned perpendicular to the nori. Gently fluff the rice, then add about ½ cup into the mold. Use the musubi lid to gently but firmly press the rice down until it’s ¾ to 1 inch thick. It should hold together but not feel dense. Sprinkle a ¼ teaspoon of furikake evenly over the surface. Carefully unmold the rice, then add a slice of glazed Spam on top.

Fold one end of the nori over the Spam and rice stack. Lightly brush the edge of the opposite nori with water to help it stick, fold over, then press to seal where the ends overlap.

The musubi tastes best served warm right away, or you can individually plastic wrap to enjoy on the go.