Bring a pot of water to a boil and gently add the eggs. Boil for 6 minutes.
Transfer the eggs to an ice bath and allow them to cool completely.
Peel the eggs carefully, making sure not to damage the whites.
In a small bowl, mix soy sauce, mirin, chilli flakes, sesame seeds and water to create the marinade.
Place the peeled eggs into a resealable plastic bag or container with the marinade, ensuring they are fully submerged.
Refrigerate for at least 12 hours, or up to 3 days for a stronger flavor.
Remove eggs from marinade, slice in half, and serve with ramen or as desired.