I believe your child's age should be specified in the booking. I've only traveled to Japan on my own, but ANA's booking tool lets you say how many passengers are 0-1, 2-11, 12-15 or older. ANA *does* let you pick out a child meal, but you have to take care of that in advance online or by phone.
More info on their website.
They ought to have a version of the kids meal for F. If they don't,
consult their website and figure out what they are serving that might work for your little one. Rice crackers or burgers or curry, for example. You can check out the full menu for your flight at the bottom of the page and see what you can mix or match among the light meal offerings. Since you're in F, I don't want to give the Y answer and say "well, just bring something."