Roberta Oaks never gave much thought to menswear until she opened her eponymous downtown women’s boutique. At lunch hour, she enjoyed the parade of pedestrians passing by her picture window, and what struck her was the sameness of men, young and old, in boxy aloha shirts.

"The color palette looked old, really drab blues and grays, and I thought it was unfair that men were expected to wear an aloha shirt, but limited to what was available. It seemed like there was room to do something fun and more stylish," she said.

She launched her first men’s shirts in summer 2010, and the men’s looks have taken over half her shop. Others have taken notice and this year Oaks has two summer collaborations going, with Urban Outfitters and POW!WOW! Hawaii, her fourth project with the arts organization.

The POW!WOW! hand-numbered, limited-edition shirts deliver the option of going full-color tropical or black-and-white to suit urban style, at $115 each.

RO for Urban Outfitters features three prints: a muted "Going Pineapples" print, a print ode to Tom Selleck’s "Magnum, P.I."-style shirts, and "Twilight Palms," priced from $115 to $120.

Oaks said Urban Outfitters approached her with the desire to bring more local style to its Waikiki boutique.

"Roberta’s taken something that’s unique to us but has given it global appeal," said John Ridgeway, a fashion aficionado who happened to be shopping in her boutique during our interview.

Oaks has learned not all men want to share the secret of their new chic look.

"I’ve had men come in and go, ‘Oh, this is where he shops,’ explaining that they know people who, when asked where they get their shirts, are really vague about it."

RO for Urban Outfitters shirts are available at Urban Outfitters Waikiki in the Hyatt Regency Hotel & Spa, the Roberta Oaks boutique at 19 N. Pauahi St., or at robertaoaks.com. RO for POW!WOW! shirts are also available at the boutique, her website or powwowhawaii.com.