In a bowl, whisk together eggs, water, dashi powder, mirin, soy sauce, and salt until fully combined. Strain the mixture through a fine mesh strainer to ensure a smooth texture.

Divide sliced shiitake mushrooms, shrimp, and edamame among heatproof bowls, reserving a few shrimp and edamame for topping.

Gently pour the strained egg mixture over the fillings. Remove any surface bubbles with a spoon and cover each bowl tightly with aluminum foil.

Place the bowls in a pot and add water until it reaches halfway up the sides. Cover the pot and bring to a boil over high heat.

Reduce heat to medium-low and steam for 5 minutes. Turn off the heat, uncover briefly to add the reserved toppings, then cover again and simmer for 3 more minutes.

Turn off the heat and let rest, covered, for 5 minutes before serving.