I can't believe I forgot about this place, on Grant between Sutter and Bush, but it all came back to me when Japanese friend took me there for lunch yesterday.
Mikaku has a varied menu, including lunch stuff (donburi, udon/soba, etc.), sushi, and even a board of those small dishes (like we were hoping to get at Tekka). I had katsudon (batter-fried pork cutlet over rice). It was your basic katsudon, which is high praise. There are some special places in Japan that make pork cutlet an art form, but for everyday lunch you don't want anything fancy.
My friend's order was interesting because she chose Tendon -- tempura donburi (assorted tempura stuff over rice) -- and was asked to specify Japanese or American style. Further inquiry disclosed that American style is the same thing except it has Teriyaki sauce poured over it. "Americans like it sweet," said the waitress in Japanese, though when she saw the look on my face she added, "well, a lot of them do."
Like many Japanese restaurants, Mikaku serves miso soup before the main course to non-Japanese customers, and at the same time as the main course for Japanese customers. If the table is mixed, like it was yesterday, they ask. We both asked for the soup at the same time as the main course.
The board of special side dishes said "Dinner only," but the sushi chef told the waitress it would be ok to order a couple dinner things if the chef in the back said it would be ok. The chef in the back said ok. We got shiokara (squid marinated in its own guts with sake) and also buta no kakuni (pork belly simmered until soft and marinated in soy sauce and sake). The shiokara was more orange than the pinkish one Tida described at Lakuni a while back, and was a little more "gutsy" tasting. The buta no kakuni was soft but a little too salty - maybe that was because he wasn't really prepared to make it. I'm betting the kakuni at Tekka will be better.
All in all, Mikaku is good dependable place for Japanese lunch, not too far from Union Square or the financial district.