Nippon Building Fund Inc. (hereinafter "NBF") was formed on March 16, 2001 as an investment corporation under the Law Concerning Investment Trusts and Investment Corporations of Japan (hereinafter the Investment Trust Law of Japan) with Mitsui Fudosan Co., Ltd., Sumitomo Mitsui Trust Bank, Limited. and Nippon Building Fund Management Ltd. (hereinafter "NBFM") acting as sponsors. Registration with the Kanto Local Finance Bureau of the Ministry of Finance was completed on May 10, 2001 and NBF started acquisition of office properties on May 23, 2001. NBF is an externally managed real estate fund, formed as an investment corporation. NBFM, as NBF’s asset management company, is engaged in acquiring, managing, leasing, and renovating office properties. Mitsui Fudosan Co., Ltd. currently owns 46% of NBFM while Sumitomo Life Insurance Company owns 35% and the remaining 19% is mainly owned by financial institutions. On September 10, 2001, NBF had raised approximately ¥50,000 million through an initial public offering of units. Those units are listed on the J-REIT section of the Tokyo Stock Exchange. As of June 30, 2025, NBF had ownership or beneficiary interests in 68 office properties containing approximately 1,207,586 square meters of rentable office space. As of June 30, 2025, NBF had leased office space to 1,545 tenants engaged in a variety of businesses. The occupancy rate for the office properties was approximately 98.6%.