* Superlong outperform, steepener unwound * Some see BOJ disappointment given high expectations * Short-term notes could be hit if BOJ does not cut rates By Hideyuki Sano TOKYO, Jan 21 (Reuters) - Long-dated Japanese government bond prices gained on Monday, ahead of the Bank of Japan's policy announcement, as players took profits on their bets the yield curve would steepen. Traders said some market players seem to be worried the BOJ may not live up to unusually big market expectations for its two-day policy meeting ending on Tuesday, an outcome that is likely to hurt share prices and benefit low-return bonds. "Looking at price actions, it seems like the bond market is betting that there will be some disappointment in the stock market tomorrow," said a bond trader at a Japanese brokerage. The 10-year JGB futures contract rose 0.16 point to 144.41, moving toward Thursday's intraday high of 144.50, which was its highest since Dec. 13. In the cash bond market, longest maturities such as 30-year bonds, outperformed shorter peers, in a move driven by the swap market, where some players took profits from steepening bets. As the 30-year swap rate fell sharply, the 30-year bond yield fell 3.0 basis point to 1.970 percent while the 10-year yield fell just 1.5 basis point to 0.735 percent . Japan's Nikkei share average slipped more than 1.5 percent on Monday, also on profit-taking ahead of the BOJ's decision. On Friday, it had reached a 32-month high after its biggest one-day gain in nearly two years. Investors expect the BOJ to set a 2 percent inflation target and increase its asset purchases and make an open-ended commitment to them. Some think the BOJ could cut interest rates on excess reserves or expand the target of its asset purchase. "The market has partially priced in the chance of cutting rates. So if the BOJ doesn't, short-term bonds may stumble a bit," said Toru Yamamoto, chief fixed income strategist at Daiwa Securities. The two-year JGB yield hit a 7 1/2-year low of 0.070 percent on Friday on growing expectations the BOJ might cut or scrap its 0.10 percent interest payment on excess reserves. The two-year notes were untraded on Monday. But Yamamoto said that losses will be limited because the market will think the BOJ will take such a step after a new governor takes over from current chief Masaaki Shirakawa, whose term ends in April. Also on Tuesday, the Ministry of Finance will hold some of its regular periodic meetings with primary JGB dealers. "I think the main topic should be fiscal year '13 budget formation and JGB issuance schedule," said Naomi Muguruma, senior strategist at Mitsubishi UFJ Morgan Stanley Securities. "The timing is not related to the BOJ meeting, it's that the government at the end of last week is mostly done with fiscal year '13 budget blueprint."