The various establishments known collectively as “family restaurants” are Japan’s answer to the American chain restaurant. Housed in large buildings with substantial parking lots, well lit, and sometimes open twenty-four hours, they bear little resemblance to more traditional Japanese eateries. Given that the traditional Japanese restaurant has a nearly invisible storefront, no parking, and rather limited hours, this is a large part of their appeal.
Family restaurants serve a mix of Western, faux-Western, and Japanese cuisine, featuring both teishoku set meals and individual items (tanpin). The quality is what you would expect from a national chain -- nothing terrible, but nothing very good either. They tend to be a little more expensive than smaller independent establishments, especially considering the food quality. But the diverse menus make them a good compromise for groups with differing tastes.
One thing the family restaurant has a near-monopoly on in Japan is the drink bar -- they are just about the only place in the country where you can find soda and juice served on an all-you-can-drink basis. They are quite popular with high-school students.
Family restaurants are common around train stations and on major highways. They are almost all owned by a few regional or national chains. Here are some of the more common ones:
Denny’s -- Japanese Denny’s is a cut above its American progenitor, and one of the very few places you can find something approaching an American breakfast. Aside from that, there is no resemblance at all.
Skylark/Gusto -- A set of interrelated chains that closely resemble each other. Skylark features a seasonally varied Japanese menu and a fairly consistent Western menu with actual steak, hamburger steak, and a chicken item or two. They also have the family restaurant standards: fried potato, karaage (Japanese fried chicken), and various gratin dishes.
Jonathan’s -- Jonathan’s has a somewhat more extensive Japanese menu than Skylark, and a correspondingly smaller Western menu. Otherwise, they are much the same.
Bikkuri Donkey -- The menu is almost entirely made up of hamburger steak, served on a sizzling iron plate. A solid bet if you want a filling, affordable meal and do not need variety.