This summer, Japanese real estate investment trusts benefited from an unexpected group of net buyers for the first time in nearly seven years: Mom and pop investors.

Encouraged by the relatively lucrative returns, an increasing number of retail investors are putting their money in some of 58 publicly traded REITs tracked by the Tokyo Stock Exchange's gauge. Individuals were net buyers in July for the first time since November 2011, according to TSE data. They invested a combined ¥52 million ($476,000), a turnaround that strategists say is likely to have continued in August.

While the size of investment is dwarfed by the ¥8.7 billion in net purchases by other financial institutions, the increased presence of retail investors in a ¥10.4 trillion market that has traditionally been a place for institutions hints at a growing appetite for alternative investment vehicles among Japanese citizens — whose world-beating longevity means decades of retirement.