I use a ton of egg whites, so this is the way I store leftover egg yolks for later use.
I use a lot of egg whites to make macarons or financiers, and thus our egg consumption is unbalanced.Since it's just the two of us, this method also helps to extend the shelf-life of my milk.
Defrost naturally or under cold running water. When using this to make bread or sweets, measure it properly.
Enjoy Japanese food around the world.