Bain Capital is launching an unexpected $4.3bn counterbid for IT company Fuji Soft, reigniting Japan’s most fiercely contested takeover battle of the year with a renewed challenge to rival private equity group KKR.

U.S. private equity firm Bain Capital will raise its offer price for Japan's Fuji Soft by around 1.6%, it said on Wednesday, trumping a recently increased tender offer bid from rival KKR. Bain's increased offer price,

Bain Capital is increasing its offer for Fuji Soft Inc. with a bid that values the Japanese software company at $4.3 billion, extending a rare battle with KKR & Co. in the country’s booming buyout market.

Bain Capital is increasing its offer for Japanese information technology company Fuji Soft Inc., people with knowledge of the matter said, prolonging a rare bidding war with KKR & Co. in the country’s booming buyout market.

KKR and Bain have been competing for Fuji Soft. KKR announced last month that it would offer 1 yen higher than Bain's earlier bid. Fuji Soft's board of directors unanimously expressed a supportive opinion of KKR's offer, recommending that shareholders tender their shares.

U.S. private equity firm Bain Capital is set to raise its offer price for Fuji Soft to 9,600 yen ($63.35) from 9,450 yen to counter KKR's tender offer bid, the Nikkei business daily reported on Wednesday.