South Korean low-cost carriers Air Busan and T'way Air Co. will set up new routes to Japanese cities as part of efforts to offset declines in demand from China, the companies said Friday.The number of Chinese travelers has sharply declined following the ban on all travel packages to South Korea from March 15 onward amid a row between Seoul and Beijing over the planned deployment of an advanced US anti-missile system on the Korean Peninsula.An undated file photo of a South Korean budget carrier T