Morgan Stanley has bought Citigroup Inc.'s Tokyo headquarters to boost its Japanese property portfolio.

A Morgan Stanley real estate fund purchased the 22-story building near Tokyo Bay, said Natsuo Nishio, a Tokyo-based spokesman at Morgan Stanley. The fund paid ¥48 billion for the property, three people with knowledge of the sale said, declining to be identified because the price hasn't been publicly announced.

Morgan Stanley is buying the property as Tokyo office vacancies near a seven-year low, with a shortage of high-grade office space pushing up rents even as economic growth slows.

Citigroup will sell and lease back its Tokyo headquarters to reduce risks associated with holding assets, the New York-based company said Tuesday in an e-mailed statement.