By Makoto Furuno / Yomiuri Shimbun Staff Writer TAKETA, Oita — As Oita Prefecture touts itself as the top destination in Japan for onsen hot springs to lure visitors, one city is promoting its unique local waters to take advantage of the national movement toward “health tourism.” The city of Taketa promotes the health aspect of its Nagayu hot springs, which has a quality that is rare even in Japan, and hopes to take some of the spotlight from well-known hot spring resorts such as Beppu and...