Japanese e-commerce firm Rakuten Inc said on Tuesday it would buy U.S. Rakuten expects the transaction to close next month, the company said in a statement. CEO Hiroshi Mikitani has led Rakuten on a buying spree to reduce the firms reliance on the domestic market. High-profile acquisitions in recent years have included free messaging application Viber for $900 million and Canadian e-book reader Kobo for $315 million.