(Refiles to fix literal in headline)
* Kumagai Gumi jumps on brokerage rating hike
* Topix's rebalancing may contribute to volume rise after 3 Japan Post stocks to be added to index - traders
By Ayai Tomisawa
TOKYO, Dec 29 (Reuters) - Japan's Nikkei share average was flat in choppy trade on Tuesday morning, though stocks which are more sensitive to domestic demand such as construction companies outperformed more global, cyclical counters.
The Nikkei was flat at 18,873.27 points at the midday break, and looked set for a gain of around 8 percent for 2015.
Traders said that investors may not take large positions before the last trading day of 2015 on Wednesday, but they would focus on stocks with individual news.
The construction sector attracted buying, with Kumagai Gumi jumping 6.7 percent after Daiwa Securities raised its rating to 'buy' from 'outperform', citing its strong first-half operating profit and brisk domestic construction demand.
Other stocks in the sector followed, with Kajima Corp rising 2.0 percent and Taisei Corp advancing 0.9 percent.
Exporters were mixed, with Toyota Motor Corp dropping 0.8 percent, Nissan Motor Co rising 0.1 percent and Canon Inc gaining 0.4 percent.
"We don't see big catalysts today, but there is Topix's rebalancing at the market close, so there might be a volume increase," said Chihiro Ohta, general manager of investment research and investor services at SMBC Nikko Securities.
At the end of the market close, three Japan Post stocks, Japan Post Bank Co, Japan Post Holdings Co and Japan Post Insurance Co, which debuted in November, will be added to the Topix index.
"Although the market impact is unknown, higher volume is expected in these shares," Ohta said.
Retail company Cocokara Fine Inc jumped 4.6 percent after the Nikkei business daily reported that the company's pre-tax profit likely more than doubled to about 14 billion yen for the year through March.
The broader Topix rose 0.2 percent to 1,532.06 and the JPX-Nikkei Index 400 added 0.2 percent to 13,824.52. (Editing by Kim Coghill)