Japan is so varied that it can be hard to find an “authentic” Japanese experience. Sure, a lot of people do visit all the big food chains like MOS Burger and Yoshinoya; people go to ramen restaurants and order out (distinctly Japanese) pizza. But for day-to-day food, Japanese families usually cook at home. Where can you find that experience?
I can't guarantee that it's the same as a family meal, but the closest thing to it might just be Ojou. A very small restaurant with only a handful of tables, it's a business run from a family home. The restaurant is split between two rooms, one of which has a counter and low tables on tatami, both of which are decorated simply. One room in particular feels homely, with a TV in one corner and a few shelves of manga (One Piece is popular everywhere) and books. It's already much better than a chain store.
The menu is roughly the same as a chain store, based around staples of Japanese food – bowls of noodles, katsu (breaded, fried food) and rice bowls, but at Ojou they also serve sushi. In fact, it was originally a sushi restaurant. The prices aren't much higher than their commercial counterpart, but the quality and size of the portions are noticeably better. They offer a wide variety of meals, so there's something to suit everyone. They also serve a range of alcoholic drinks, from plum wine to beer to cocktails.
My first meal there was a pork katsu with a twist. Instead of being served with the rice in one bowl, the katsu was served separately, sizzling hot, on a small, iron griddle. It came with soup and some vegetable pickles, all beautifully presented on one, big tray. It was so delicious I couldn't eat it fast enough, although personally I wasn't a fan of the soup. It was a refreshing change to have simple Japanese food made with care and attention, and served in bowls that weren't all made of plastic. After several visits, I've not had a bad meal there yet, and every time I've left with a full stomach and a smile.
They don't seem to have a huge local presence, despite the enormous signs that intrigued me enough to go, but they do appear to have some regulars. It's a relaxed place to take your time eating a delicious, simple meal.