TOKYO, April 16 (Reuters) - Japanese private equity fund Unison Capital is set to bid for at least one-third of wig maker Aderans Holdings (8170.T), raising the prospect of a proxy fight with U.S. hedge fund Steel Partners, the Nikkei business daily reported on Thursday 16 April.

Aderans shares were untraded due to a glut of buy orders after a brief suspension by the Tokyo Stock Exchange.

Steel Partners, Aderans' top shareholder with a stake of about 27 percent, has proposed the replacement of the struggling firm's management at a shareholders meeting next month.

Aderans management would endorse Unison Capital's offer and accept board members from the fund, the Nikkei said.

As early as June, Unison Capital would offer to buy a stake in Aderans for 1,000 yen per share, 30 percent above its average share price for the past three months, costing the fund at least 14 billion yen ($141 million), the Nikkei said.

Aderans said nothing had been decided on the matter and it declined to comment further.

Unison Capital officials were not immediately available.

Steel Partners succeeded at a shareholder meeting last May to oust Aderans' managers, in the first such case of Japanese management being ejected under pressure from an activist fund.

Aderans has said it was likely to report a net loss of 2.1 billion yen for the year ended in February, with its main wig business hurt by the economic slump.

The company is scheduled to announce its results at 0600 GMT on Thursday.

Shares in Aderans were bid at 955 yen, up 1.1 percent. ($1=99.32 Yen) (Reporting by Gerald E. McCormick, Taiga Uranaka; Editing by Rodney Joyce)