A Tokyo-based construction company has purchased Vista Modern, a four-story, 34-unit apartment complex in Sherman Oaks, for $16.5 million or about $485,600 per unit. RBM of California Inc., the Los Angeles subsidiary of Residence Building Management Co. Ltd. In Tokyo, paid all cash, said Hirotaka Kobayashi, president of the RBM. The firm owns two other multifamily properties in West Los Angeles, he said. Because the complex is less than a year old, the buyer paid a premium: Similar properties in the area are selling for around $400,000 per unit, according to real estate data provider CoStar Group Inc. “We saw opportunities in 2012 to diversify our assets so we came here,” Kobayashi said. “Our long-term plan is to invest in areas with populations that are growing, like Los Angeles.” The seller, developer DNN Capital Inc. of Los Angeles, completed the property at 4632-4646 Vista Del Monte Ave. last December, said Janette Monfared, senior associate in Marcus & Millichap’s Encino office. It was about 80 percent leased at the time of the sale. Monfared and Jeff Louks, senior vice president of investments at the Calabasas-based brokerage, represented both sides of the transaction. “There are very few brand-new construction projects in really good areas that come up for sale,” Monfared said, explaining that the buyer was found less than a month after the property went on the market.