Citigroup Inc.’s (C) Japanese private equity arm has restarted efforts to sell the country’s largest call center company, Bellsystem24, by market share, with the first round of bidding due to close September 1st. Global buyout firms including Permira and KKR are set to bid for the company, grabbing a rare opportunity to chase big investments in Japan.

Around 20 buyout firms have reviewed the books of Bellsystem24, but only four or five may submit formal bids next week due to the deal size. Besides Permira and Kohlberg Kravis Roberts & Co, potential bidders include CVC Capital and Bain Capital. Some other firms, though not actively working on the deal at present, may enter the race if invited to partner prominent bidders.

Japanese mega-banks, which include Mitsubishi UFJ Financial Group (MTU) and Mizuho Financial Group (MFG), which were hurt less by the global financial crisis, are willing to lend money.

At present, both KKR and Permira believe the $1.5 billion estimated valuation by Citigroup is too high, as there are concerns regarding the real value of the assets.

Nikko Citigroup, the Japanese investment banking arm of Citigroup, and Goldman Sachs Group Inc. (GS) are advisors for the transaction.

The move to sell Bellsystem24, valued at about $1.5 billion, comes as a part of the restructuring undertaken by Citigroup. The company aims at shedding a part of its operations that it considers non-core assets to bolster its capital base in the wake of the global credit crunch.

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