Mitsui Fudosan Co., the nation's biggest developer by sales, said it plans to triple the size of its private real estate investment trust in three years as the company seeks to tap Japanese pension funds.

Mitsui Fudosan Investment Advisors Inc., an asset management unit of the developer, plans to increase the private REIT to ¥200 billion in three years from ¥76 billion, said Akira Ikeda, a managing director at the Tokyo-based company. The private REIT drew about 40 institutional investors, including banks, insurers and pension funds, he said.

Mitsui Fudosan joins Mitsubishi Estate Co., Japan's second-biggest developer, and Nomura Real Estate Holdings Inc. in building up their private REITs to attract Japanese pensions seeking to diversify their assets. A total of ¥91.8 billion in share sales by Japanese REITs have already been announced this year, according to Deutsche Securities Inc.