How is Soy Sauce applied in a restaurant

How is Soy Sauce usually applied in a restaurant in Japan, like is it usually on the table for you to use once the food arrives or is up to the chef and applied by the chef themselves. The reason i ask is because all my anytime that i buy and eat instant ramen or udon from my local convenience store i always end up with a bad headache so i always thought that the reason is because of the aijinomoto (MSG) that's in the broth. However recently i came across a recipe for some homemade ramen so i made without the msg and i still ended up the headache so i looked at my ingredients to figure out why and i found on my soy sauce it contained 575 mg of sodium and i used 2 tablespoons of it so i'm thinking it's probably the sodium or the soy sauce itself that's causing the headache. Which brings me back to my original question how is soy sauce applied. Because if i can avoid the soy sauce or high sodium while im in Japan next year i think i'll be ok and i could avoid the headache any tips?

Depends on the dish. With sushi, for example, you use soy sauce as dip sauce, so a bottle is on the table for you to use. But in ramen or other dishes such as teriyaki chicken (just as an example) soy sauce is already IN the dish, as part of the flavoring.

I hope you find out where it is coming from - look up Tyramine; this seems to be a substance that tend to lead to headaches in some people, contained in: cheese, pickles, processed meat, chocolates, alcohol (esp. red wine), grapes, soy sauce, peanut butter, and citrus fruits.

Regular soy sauce is high in sodium. But you should/might be able to find low sodium versions (which are still awfully high). Another test to see if that's what's bothering you is try eat some Cup Noodle or any packaged ramen. That stuff is all super-high in sodium (read the label for a shock). But if you can eat Cup Noodle or other ramen, then it's not the sodium that's the problem. You could have a reaction to the soy beans. Look for fresh soy beans and steam them, to see if eating them gives you any trouble (but they do taste best with salt). You might be able to get frozen soy beans. The Japanese word is eda-mame (eh-dah mah-may). If none of that helps you figure out the problem, it must be something you didn't think of. If all else fails, and you still want to eat that stuff, take some pain killers, like ibuprophen (but NSAIDs can cause stomach problems) or paracetamol, a half hour or so ahead of time.