This is another topic where people are trying to rewrite the history of Japan. The Wiki states Yakiniku was introduced by Koreans to Japan, Totally not true. I tried to change the Wiki but someone has a spambot like a thing that re-uploads his document every hour. The Wiki is a propaganda billboard for keyboard warriors. I can only put the truth here:
Anyway, Japan has had a meat-eating culture from the Jomon period. They have found evidence that they ate deer, turtle, and birds. In fact, Japan ate meat until Buddhism was introduced to Japan and the shogun at that time banned the eating of meat under Buddhist vegetarian principles. However, the shogun's power could reach only so far so many places that here remote from the cities and far from the sea ate meat because fish was not available and the shogun's rules were not vigorously enforced in these far away places. Also, some meats were excluded from being banned because of various reasons; eggs for some reason were not considered meat. Whales were considered fish and were not banned and eating horse meat was allowed as part of a ritual. The ban on meat lasted for several hundred years so many generations grew up without every tasting meat, but when the west arrived in Japan, meat-eating reemerged though not popular at the time. At the time, the forerunner to Sukiyaki was invented. After WW2, western cuisine became popular and most such dishes had chicken or pork. It is said that the inventive of Tonkatsu(Ton = pork + Katsu = Cutlet) was originally planning a BeefKatsu but gave up feeling the red meat was too 'meaty' for Japanese people and switched to pork instead. Other notable meat dishes that became popular at the time were ShabuShabu, Yakitori, and Hambagu. Also, after the war, Japan began to develop its own Wagyu beef industry and in support of this industry, Yakiniku(Grill meat) Restaurant began opening up. The original Yakiniku Restaurants would have a chef at a teppan table with customers seated around. The Chef would prepare the steaks and serve the customers. This TeppanYaki is now famous around the world even without serving Wagyu Beef.
Korean Calbi restaurants in Japan did play a part in Yakiniku history but not as the origin of meat eating. The first Calbi Restaurant opened after the war in Japan. The unique thing about the restaurant was that people cooked their own food at their table using a griddle. People at home sat around n Irori(fire pit) and cooked food but never cooked there own food at a restaurant. This was the original draw of the Calbi places since meat was virtually never ordered for the first few years - the first Calbi restaurant survived by selling fish and seafood until gradually the nation became more and more accustom to eating beef. In other words, Carbi Restaurants did not introduce eating meat to Japan, they gained popularity as a fall out of the overall trend of meat consumption influenced by the growing popularity of western cuisine.
Today, Yakiniko places and Calbi places are virtually the same. They both want to make money so they expanded their services to include the dishes and style of the other. You can get Kimchi and bulgogi at Yakiniku places and you can get a chef to cook you Wagyu at a Calbi place. The main difference now a day is that Yakiniku places tend to be classier joints while Caslbi places are more after work eat and drink places.
So in summary, eating meat has a long history in Japan. The practice was re-popularized do to contact with the west while the cook at table style of restaurants was introduced by Korean Calbi restaurants.