01 - Bring a pot of water to a rolling boil.
02 - Gently lower the eggs into the boiling water using a spoon. Boil for exactly 7 minutes for a slightly runny yolk.
03 - Prepare an ice bath. Immediately transfer the cooked eggs to the ice bath and cool for 5 minutes.
04 - Carefully peel the cooled eggs, taking care to keep them intact.
05 - Combine soy sauce, water, mirin, and sugar in a zip-top bag or small container. Stir until the sugar completely dissolves.
06 - Place the peeled eggs in the marinade, ensuring they are fully submerged. Marinate in the refrigerator for at least 4 hours, preferably overnight, turning occasionally for even coloring.
07 - Remove eggs from marinade, slice in half, and serve atop ramen or as desired.