TOKYO : The Bank of Japan, after clearly signalling last week's interest rate hike, may return to its accustomed fuzzy guidance about central bank policy to maintain flexibility when it eventually begins to consider how much tightening is enough. The BOJ fumbled its communication in December, surprising investors when it left rates steady, but then telegraphed Friday's increase so unambiguously that markets had 90 per cent priced it in and took the move in stride. That shift to clearer guidance,