Fujitsu officially opened their new ebookstore on Wednesday,
They're calling BooksV Japan's largest ebookstore, and with 300k articles (available through magazines, research reports, and statistical reports) it might be. Content is drawn from a partnership with Dai Nippon Printing Co., Ltd. (DNP) and DNP's affiliate, MobileBook.jp Inc. It's spread across a number of genres from fiction to technical and scientific publications. You can also find a number of magazines in BooksV, including Weekly Diamond, Weekly Toyo Keizai, and Nikkei Weekly.
it's not clear what formats are supported, but the press release days say that apps are available doe Windows and Android.