[steel]

For tamago kake gohan most people mix the beaten egg and soy sauce in a small saucer and then pour it over the white rice. However, there is no hard and fast rule for this dish.

About pouring soy sauce directly onto white rice ... if you have not witnessed it, then it would not be surprising. When I indicated that sometimes young kids might be allowed to do it on occasion at home, there are plenty of households who wouldn't even allow it at all (or admit to it). And, regardless, certainly not in front of a guest or even a homestay student etc. It's considered very poor form to do so. So, if/when Japanese do this (as it doesn't necessarily taste bad), they do so in the privacy of their own homes away from prying eyes.

Although it might not sound as appetizing, the preferred spartan condiment of choice - when there is nothing else - are Japanese pickles ... which includes the solitary umeboshi ... Hinomaru bento.