Boil the houtou noodles, drain, and freeze them using rapid freezing for 45 minutes. Store in a freezer bag.

Boil water in a pot, add the frozen houtou noodles, and cook until heated through. Drain the water.

In a microwave-safe container, combine cream cheese and milk. Cover loosely with plastic wrap and microwave at 600W for 40 seconds. Mix until smooth.

Add the cooked houtou noodles, mentaiko, and soy sauce to the cream cheese mixture. Mix thoroughly.