This is true, and I would add that, particularly in the Kansai region (Osaka area), tipping is considered offensive, because it implies that the restauranteurs would not be providing good service otherwise. OTOH, restaurants there are generally more expensive than in the US, even with the recent dollar/yen reset, with the exception of the "family" restaurants like Denny's and Saizeri-ya, which cost about the same in Japan as in the US.
One of my favorite restaurants was Yoshinoya where everyone sat around a central food preparation area. You in essence got restaurant style service for fast food prices. Don't know about now, but it was then considered sort of a hang-out for construction workers and the blue collar crowd.
Their beef bowls, however, were very, very good and I'd often take one of my daughters with me. As you might imagine, my choice of dining companions ensured excellent service as well.