You definitely do not want to boil Japanese cotton. It will fall apart if you do.
Also, when you get it you'll notice that it has sort of a skin-like outer layer. Carefully peel that off of both sides. It won't hurt you, but it doesn't wick well and makes the cotton harder to roll and fluff.
And as a final tip, DO NOT buy Japanese cotton from vape shops. They will rip you off to no end. Go to a beauty supply store. Japanese cotton was developed as a makeup remover that works better than cotton balls. You can get 60 sheets of Koh Gen Do from most beauty supply stores for around $12.