A notable boost to Kaka'ako's population began yesterday as the first residents of the twin-tower Moana Pacific condominium picked up keys and moved into their new homes in the sky.

"We're really jazzed," said Marilynn Taniyama, a third-grade teacher at Maryknoll School who sold her 'Aiea home of nearly 30 years to buy a two-bedroom unit in the 46-story building with her husband, Jerry. "It's really a new beginning for us. It's exciting."

Other owners included young professionals, recent Mainland transplants, investors and more empty nesters like the Taniyamas — an estimated 2,000 or so people who over the next few months will settle into their units in the oval-shaped towers sided with slivery gray glass.

The towers near McKinley High School on the block bordered by Kapi'olani Boulevard and Pi'ikoi, Pensacola and Kamaile streets will add people and traffic to a growing neighborhood that's shifting away from industrial uses to a mix of retail and residences.

The project's 720 units make it the third-largest residential high-rise condo project on O'ahu after Kukui Plaza and Waikiki Banyan, which were developed in the late 1970s, according to state Real Estate Commission records.

Moana Pacific is also the third condo tower to sprout in Kaka'ako during Hawai'i's recent boom. The first two, Hokua and Ko'olani, opened early last year makai of Moana Pacific. Five others are planned or under construction in Kaka'ako, while several more are planned or under construction in Waikiki and downtown.

John Jacobson, a research analyst with Prudential Locations LLC, said the impact on O'ahu's real estate market of such a large condo will be that many people will be moving out of homes, apartments and other condos, though the greater effect on the market won't be huge.

"With our continued growth of the condo inventory, the (new) building is a relative drop in the bucket," he said, adding that there were more dramatic condo development booms in the late 1970s and late 1980s.

Moana Pacific was developed by KC Rainbow Development Co. LLC, a company formed by high-tech entrepreneur Fred Chan. Units were sold for prices ranging from about $300,000 to almost $3 million.

Chan bought the 6.2-acre property in 1998 for $26 million with the idea that the site — once the home of Rainbow Chevrolet — could become a research center. But the hot housing market altered his plan and led to Moana Pacific.

Residents are expected to trickle in over the next few months. Yesterday, the 360-unit west tower opened. About 230 buyers completed their purchases, and the rest are scheduled to follow soon. The 360-unit east tower, still undergoing mostly interior work, is expected to open in March.

With landscaping still under way, walls still being painted and major work yet to be completed on the pool and other recreational amenities, many Moana Pacific owners arrived. Some just picked up keys. Others came with suitcases or small packages of household items. A handful met moving vans full of furniture and planned to spend the first night in their new homes.

Kwong Reece, a retiree who moved to Ko Olina Resort & Marina from California in 2004, was carrying boxes to her new unit yesterday and planned to move in tomorrow. She said she bought a Moana Pacific unit "because it's so close to everything."

Maria Maldonado, 73, said she bought because she needed to downsize after her mother, who had been living with her at home at The Peninsula in Hawai'i Kai, died. Maldonado, a real estate agent who moved to Hawai'i from California in 2002, picked up her keys yesterday, and also planned to move in tomorrow.

Taniyama, the Maryknoll teacher, said she had expected to live out her life in the house she and her husband bought new in Newtown Estates in 1979. But their two children grew up and moved out and the rush-hour commute worsened. So nearly three years ago, they waited in line overnight for the chance to buy a unit at Moana Pacific.

"We thought we would never move from 'Aiea," she said. Now Taniyama is thrilled to be living a short walk from Ala Moana Center, Ward Theaters and Ala Moana Beach Park.

"We're walkers," Taniyama said. "We're going to walk all over the place."

Reach Andrew Gomes at agomes@honoluluadvertiser.com.