I made this quick sketch just to try these beautiful and innovative Muji gel pens that can be erased just by friction. They write beautifully and they don't leave signs when erased.
I used the Muji pen in my long time favorite notebook. It's an Ogami professional. Its paper is not real paper. This means that it's not made of cellulose but of stone instead. This means you don't have to cut trees to make it, it is completely water proof and almost unbreakable.