While it is possible that rice may not be a part of breakfast except in the form of Rice Krispies, more often than not, left-over rice from dinner is used much like we dumb-ass westerners use bread, toast or a bagel for breakfast.
Lunch - there's rice again... and maybe we non-Japanese are having a sandwich. Maybe.
Dinner - rice for the Japanese... no matter what, it's there. For us westerners... maybe we have rice. Maybe we have yams, sweet potato, noodles or some other starch - but we mix it up. Bread may be involved, but it's not a given.
But in Japan, it's rice two to three times a day, seven days a week, every single day of the month, and every month of the year and every single year of your life until you die urinating in a rice field.
I asked various Japanese people - men, women, kids of various ages, adults of various ages - and every single person refused to waver saying "No." implying they were not bored of eating rice.
"Japanese rice is oishii" (tasty) they say. Sure... why not. I still think it depends on how it's prepared, but sure, Japanese rice is pretty good - though I would be hard-pressed to tell the difference between Japanese rice, California rice, Indian rice, Chinese rice, various long- and short-grained rices, sticky and non-sticky rices, wild rices and more. But I'm betting a four-year-old Japanese kid could tell you which rice was oishii, and therefore Japanese.
So... I asked everybody: Why do you not get bored eating Japanese rice everyday?
The answer (to a T): "I'm Japanese."
Oh... of course. It's the answer to the Universal Riddle.
You do what you gotta do.
Itadakimasu! Let's eat!