Cook spaghetti in a large pot of boiling water with 1Tbsp salt. Time according to the pasta package.
Cut Shiso leaves into thin strips.
Remove the thin skin of Tarako by making a small cut and pressing or squeezing roe out with a knife or hand.
In a bowl, add loose Tarako, soy sauce, milk, melted butter, and lemon juice, and mix well.
Add strained hot spaghetti to the sauce and mix.
Place spaghetti on a plate and put cut Shiso on top.