Casual clothing giant Fast Retailing Co Ltd on Thursday revealed a steep plunge in full-year profit amid sliding sales at its once unstoppable Uniqlo chain. The company said parent-only net profit plummeted 46.8 per cent from the year-ago period to 31.52 billion yen ($253 million) and added sales slid 18.4 per cent to 341.6 billion yen ($2.74 billion).