Rice for breakfast is definitely a thing though, but it's a lot simpler than ryokan fare: in my student days, I often just had last night's leftovers with a cup of miso soup and maybe some pickles. Here's an interesting view of various actual Japanese breakfasts, although I suspect these are also towards the elaborate end of the spectrum:
https://en.rocketnews24.com/2015/02/20/whats-really-for-brea...
We tried to check out a few artisanal donut places around Tokyo since I heard they were a new thing (at the time). Most seemed to be open very at odd times (I can't remember, but maybe from like 1-3pm?). We stumbled onto a Krispy Kreme and were surprised they offered a donut served with ice cream on top. I guess it was seen more as a dessert than breakfast?
I guess I just thought people were going to Dunkin Donuts in the morning just to grab a coffee. I mean you've only just gotten up there's no way you've already done something to deserve a donut.
It feels like they are the quintessential breakfast food for feeding groups (much like pizza is). But maybe that's only a midwestern thing. But I'd be surprised because most major donut chains (Dunkin, Krispy Kreme, Tim Hortons), are not from here.
Outside of breakfast, they are generally just served as something to go with coffee and so on, but they are definitely not dessert. A snack.
Breakfast is usually the lightest meal of the day so sometimes we will have just rice and miso soup and pickles or natto.
Japanese “western” breakfast is toast and a Japanese-style fried egg (medamayaki). Maybe bacon too.
Most people I know alternate between Japanese-style Japanese, western (fried cutlets, bread, pasta, meat sauces), and Chinese (fried rice, gyoza, ramen, mabo tofu) or Korean (kimchi, yakiniku) for lunch and dinner.
There are about 10-20 dishes that pretty much every Japanese person who can cook learns to cook.