Cut the pizza cheese into 4 pieces and roll them into balls. Slice the shiso leaves. Dice the potato into small bite-sized pieces, place them in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for about 5 minutes.

While the potato is still warm, mash it into a paste using a fork or similar tool. Add milk, potato starch, and a pinch of salt and pepper, then mix well.

Add the sliced shiso leaves and dried shirasu to the mixture, then divide it into 4 portions. Place a piece of pizza cheese in the center of each portion, wrap it, and shape it into a ball.