There are many Japanese breakfasts, but when I tell people I'm making Japanese breakfast for them it's usually something like this:
Shiozakana, rice with some furikake, some sort of mini veggie side (here kinpira gobo), miso soup, and an egg. I previously fried my egg, but my nephew insisted on a 7 minute boiled egg with a mega runny yolk and he was totally right -- max yolkage this way.
See some recipes here:
Get some salmon filets, salt 'em up, and store 'em in the freezer so you can make Japanese breakfast whenever you get the cravings. I go heavy on the salt -- it should be super salty.
I've seen lots of recipes for this but this one is my favorite because of the multiple reductions.
I steam and shock chill for the easiest, quickest and cleanest boiled egg experience.