Japan's traditional hot baths are among the world's oldest businesses - and they're attracting big new money. : For Japan’s growing flood of foreign tourists, one of the top internet search terms is “onsen,” the traditional hot springs where travelers have soaked since the days of the samurai. Now some of the world’s oldest businesses are attracting big new money. Private equity funds like SoftBank-owned Fortress Investment Group LLC and Hong Kong-based Odyssey Capital Group are spending billions to tap into the appeal of traditional inns amid a tourism boom that’s ramping up ahead of next year’s Tokyo Olympics.