By Leika Kihara and Rocky Swift TOKYO, June 18 (Reuters) – Japan is ready to respond appropriately to exchange-rate moves at any time, the government’s top spokesperson said on Thursday as the yen’s renewed slide tests Tokyo’s resolve to prop up the sagging currency. “We are ready to respond appropriately to currency moves as needed at any time,” Chief Cabinet Secretary Minoru Kihara told a regular press conference, when asked about the yen’s …