0202 GMT - With Bank of Japan officials signaling a potential shift toward faster rate hikes, market perceptions of the central bank as slow-moving appears to be dissipating, says Claudio Wewel at Bank J. Safra Sarasin. That view of the BOJ has been a long-standing drag on the yen, which has been rallying over the past week after an extended period of weakness. But in spite of a number of bullish catalysts for the currency, Wewel warns that headwinds persist. These include strong U.S. data, high energy prices and concerns over the sustainability of Japanese debt, the FX strategist says, noting that all of which implies that the yen's rebound rests on shaky ground.