Bring a pot of water to a gentle boil over medium heat.
Carefully lower the eggs into the boiling water using a spoon.
Boil for 6½ to 7 minutes for jammy yolks.
Immediately transfer eggs to an ice bath and let cool completely.
Peel the eggs gently, starting from the wider end.
In a bowl, mix soy sauce, water, sugar, garlic, and ginger until dissolved.
Place peeled eggs into a container and pour marinade over them, ensuring they are fully submerged.
Cover and refrigerate for at least 6 hours or overnight for deeper flavor.
Slice in half and serve over ramen, rice bowls, or enjoy as a snack.