I bought my first Kikkoman bottle earlier today. When opening it I noticed this styrofoam ring in the cap. Do I need to keep it or remove it? Sorry for the dumb question, just wanna make sure.

I bought my first Kikkoman bottle earlier today. When opening it I noticed this styrofoam ring in the cap. Do I need to keep it or remove it? Sorry for the dumb question, just wanna make sure.