* Japan, Inc earnings to boost market in 2015 - trader * Market heavy Fast Retailing, KDDI, Softbank rise * Weak yen helps exporters shares By Thomas Wilson TOKYO, Dec 29 (Reuters) - Japanese stocks advanced on Monday as further gains on Wall Street boosted appetite for riskier assets and buoyed investors' confidence in the outlook for equities in 2015. The Nikkei benchmark gained 0.4 percent to 17,892.82 points by 0130 GMT. In a holiday-shortened Christmas week, both the Dow and the S&P 500 closed at record highs in a broad rally. Recent gains have come on the back of promising economic data that has lifted expectations of sustainable growth in the world's largest economy. That's likely to be a big plus for Japanese firms, many of whom export heavily to the U.S. market. And with Japan's Economics Minister Akira Amari calling for a corporate tax cut of at least 2.5 percent after April, corporate earnings are likely to rise in 2015, helping the market to shrug off lingering concerns about Japan's tattered finances and weak domestic demand. "Japan Inc is the next catalyst," said Gavin Parry, managing director of Parry International Trading. "Earnings in 2015 will be very good." Investors received a further boost as a Reuters survey showed that top Japanese firms are planning to use their record 233 trillion yen ($1.9 trillion) cash reserves to boost shareholder returns in 2015 rather than spend it on wage increases. In quiet trade, investors bought large-cap shares, with Uniqlo clothes brand owner Fast Retailing Co Ltd gaining 0.9 percent and accounting for over a quarter of the Nikkei's net point gains. Mobile phone carrier Softbank Corp added 0.4 percent and KDDI Corp ticked up 0.3 percent. With the yen languishing at 120.50, within sight of a 7-1/2 year low of 121.86 plumbed this month, investors also bought exporters shares. Panasonic Corp and Toyota Motor Corp advanced 0.4 percent and 0.5 percent respectively. Prime Minister Shinzo Abe's mix of aggressive monetary and fiscal stimulus has pushed the Japanese currency down by roughly a third since late 2012, helping to boost exporters' profits and making Japanese goods more competitive overseas, but adding to some firms' import bills. Market participants see the trend continuing in 2015. "The yen is really losing its shine as a risk-averse currency," said Parry. The broader Topix added 0.2 percent to 1,430.02, while the JPX-Nikkei Index 400 ticked up 0.1 percent to 12,977.65. ($1 = 120.4900 yen) (Reporting by Thomas Wilson; Editing by Kim Coghill)