How to protect white walls in UR Danchi with kids?

Just moved into UR Danchi Kawasaki and everything is WHITE walls, doors, everything …

I have two kids… and I’m pretty sure this clean white look won’t survive more than a few days if I don’t do something fast 😂

For those living in UR or rental apartments ,what’s the best renter-friendly way to protect walls?

Removable wallpaper? Clear protective sheets? Something else?

Looking for ideas that won’t damage the walls when we move out.

Help before my kids redecorate the place permanently ..