Cut off the stems of the shiso leaves and slice them thinly.

Make a slit in the cod roe with a knife and scoop out the contents with a spoon.

Mix the cod roe, fresh cream, and concentrated soy sauce in a bowl.

Boil water in a pot, add salt (1/2 tsp), and cook the spaghetti according to the package instructions. Drain the water.

Add the cooked spaghetti to the bowl with the sauce and toss to coat evenly.