Hamburgers in buns, on the other hand, are predominantly the domain of fast food chains. Japan has homegrown hamburger chain restaurants such as MOS Burger, First Kitchen and Freshness Burger. Local varieties of burgers served in Japan include teriyaki burgers, "katsu" burgers (containing tonkatsu) and burgers containing shrimp korokke. Some of the more unusual examples include the rice burger, where the bun is made of rice, and the luxury 1000-yen (US$10) "Takumi Burger" (meaning "artisan taste"), featuring avocados, freshly grated wasabi, and other rare seasonal ingredients. In terms of the actual patty, there are burgers made with Kobe beef, butchered from cows that are fed with beer and massaged daily. McDonald's Japan also recently launched a McPork burger, made with U.S. pork. McDonald's has been gradually losing market share in Japan to these local hamburger chains, due in part to the preference of Japanese diners for fresh ingredients and more refined, "upscale" hamburger offerings. Burger King once retreated from Japan, but re-entered the market in Summer 2007 in cooperation with the Korean owned Japanese fast-food chain Lotteria.