Tokyo introduction

This is a cooking method for boiling potatoes.

When potatoes are cooked, they tend to fall apart.

When they fall apart, they fall apart from the pointy corners.
So, use a peeler to remove the corners.
This is called "chamfering".
It is essential for miso soup and "Niku-jaga". This is an indispensable technique for cooking potatoes.

Wikipedia

Peeler
https://en.wikipedia.org/wiki/Peeler