In a medium pot, combine soy sauce, mirin, water, dried kelp, and sugar. Bring to a boil over medium heat, stirring to dissolve the sugar. Once boiling, reduce heat to low and let simmer for 2 minutes. Remove from heat and cool completely.

Separate the egg yolks from the whites and place the yolks gently in a shallow glass container in a single layer.

Once the brine is cool, strain out the kelp and pour the brine over the yolks, ensuring they are fully submerged. Cover the container.

Refrigerate and let the yolks cure for 12 to 48 hours, flipping them every 12 hours for even curing.

After curing, rinse the yolks under cold water to remove excess salt, pat dry, and serve atop rice with sesame oil, scallions, and nori.