* Hitachi Koki soars on report Hitachi may sell company
* Mining shares outperform after oil rises previous day
By Ayai Tomisawa
TOKYO, Dec 28 (Reuters) - Japan's Nikkei share average was flat on Wednesday morning in thin end-of-year trade, while Toshiba Corp tumbled 20 percent on continued concerns about posting a big special loss.
The Nikkei was barely changed at 19,401.70 in midmorning trade, after opening slightly lower.
Traders said that the Japanese stock market will likely stay directionless from here and is expected to end the year around the current level.
"Most foreign investors and institutional investors are on the sidelines now," said Takuya Takahashi, a strategist at Daiwa Securities.
Takahashi said that attention would be on news of individual developments such as Toshiba, which is diving again on loss worries, as well as Hitachi Koki Co, which is soaring on a media report that Hitachi Ltd is considering selling the company to KKR & Co.
Toshiba stumbled the 20 percent daily limit, extending its fall from the previous day after the company said it may have to book several billion dollars in charges related to its acquisition of a U.S. nuclear power business.
Hitachi Koki soared 15 percent after the Nikkei newspaper reported that negotiations between Hitachi and U.S. private equity firm KKR were in the final stages and that an official agreement could be reached next month.
Inpex Corp rose 1.3 percent and Japan Petroleum Exploration gained 1.7 percent. Oil gained 1.5 percent Tuesday, before edging down in Wednesday Asian trade.
The broader Topix was flat at 1,535.71 and the JPX-Nikkei Index 400 was also flat at 13,774.02.
Reporting by Ayai Tomisawa; Editing by Eric Meijer