This is a mod that adds a kotatsu with matching cushions to your game. There are two versions of this mod, one for desktop and one for mobile. 

The mobile version of this mod adds items as furniture that you can buy from the shops at the festivals. 

If you want to change your current tree or couch, select a tree or couch, and then the item you want to change. You will be given the option to change it to a new tree or couch. You can change the color and texture of your new tree or couch.