Regarding Restaurant etiquette

Will be going to Japan this April with husband and 10yo son. My son has gradually broadned his eating habits aiming specifically for this trip, as he knows our usual meals won't be available. However, there are some things he still won't eat.

There are a couple of chain restaurants me and husband would like to try but, having checked the menu, I am pretty confident he won't eat anything there. Is it a great problem for the restaurant if the adults eat and he doesn't? Obviously wouldn't dream of doing this on a smaller place but if it's somewhere like CoCo Ichiban, how would it be perceived?

Thanks in advance.

by cecilsoares