* Securities firms Nomura and Daiwa rally * NTT Docomo hits 11-year high By Thomas Wilson TOKYO, Apr 23(Reuters) - Japanese stocks rose on Thursday as investors sought to pick up stock seen as undervalued and presenting positive earnings prospects, with the likes of Nomura Holdings and large cap Japan Tobacco surging on strong demand.

The Nikkei benchmark climbed 0.3 percent to 20,190.22 after opening at a fresh 15-year high of 20,252.12.

"Investors are expecting big gains from securities firms ahead of earnings season," said Makoto Kikuchi, chief executive of Myojo Asset Management. "They look good value." Nomura Holdings rose 4.2 percent to their highest in a year, and has jumped over 10 percent since Wednesday. Daiwa Securities Group climbed 2.9 percent.

Large-cap Japan Tobacco Inc was Tokyo's biggest gainer, climbing 4.8 percent. The cigarette maker is the Nikkei's sixth largest firm by market capitalisation. Elsewhere, NTT Docomo Inc rose 2.8 percent to hit an 11-year high.

The Tokyo Stock Exchange's securities brokerage subindex rose 3.4 percent to its highest since January last year. Investors have snapped up banking, other financial shares and insurers this week, saying they look comparatively cheap.

"The banks' underperformance in the last couple of years, has left them egregiously undervalued," said Stefan Worrall, director of cash equity sales at Credit Suisse, adding that strong earnings announcements by U.S. banks may have drawn attention to the Japanese banks.

Big-name exporters Panasonic Corp and Nissan Motor Co Ltd were up 2.3 and 1.2 percent respectively, boosted by the weaker yen. The Japanese currency fell through the 120 mark against the dollar for the first time in nine days.

The positive mood offset a private survey on Thursday showing China's factory activity contracted at its fastest pace in a year in April.

Japanese stocks have risen 15.8 percent this year, driven up by expectations of higher shareholder returns and an influx of money by public pension funds.

The broader Topix climbed 0.4 percent, touching a fresh 7-1/2 year high of 1,633.81, while the JPX-Nikkei Index 400 also rose 0.5 percent to hit a record high of 14,825.53.

(Reporting by Thomas Wilson; Editing by Shri Navaratnam)