Bring a pot of water to a boil. Carefully add eggs and cook:
- 6–7 minutes for jammy yolks
- 9–10 minutes for fully set yolks
Transfer eggs immediately to an ice bath for 5 minutes to stop cooking.
In a bowl, mix soy sauce, water, sugar, garlic, ginger, and sesame oil. Stir until sugar dissolves.
Gently peel cooled eggs and pat dry.
Place eggs in a container and pour marinade over them until fully submerged. Cover and refrigerate for at least 4 hours or overnight for deeper flavor.
Slice in half and enjoy over ramen, rice bowls, or salads.