'Ukulele-strumming Nicholas Acosta, 10, is one of the youths ages 5 through 11 who will perform boogie-woogie selections at Sunday's Ukulele Festival at Kapi'olani Park bandstand.

Acosta, who will be a fifth-grader at St. Joseph School in Waipahu this fall, looks like your local neighborhood tyke. He has a cheerful disposition and shy manner. When he strums his trusty instrument — a surprise birthday gift from his nana in April — he's all heart and all joy.

But he's not your ordinary uke player. For Acosta, strumming his Kamaka meant overcoming challenges. His right arm stops where his elbow would be, but it doesn't prevent him from plucking and strumming like his chums in his uke classes at Roy Sakuma's 'Aiea studio.

Inspired and encouraged by family, the 'ukulele is an outlet for his newfound expression.

"I play with my dad and my cousin, Shawn Augustin, who's 14," Acosta said. "We sometimes jam at home and play at parties. It's fun."

Acosta executes chords with his left hand, his uke cradled beneath his right arm as he strums — he finds the up stroke easier than the downward stroke.

"I don't have problems strumming," he said. "Not really. I try to practice every day."

His 'ukulele instructor, Royanne Labuguen, 26, is amazed at Acosta's proficiency.

"When Nick first started classes just a few months ago, I didn't know what to expect. I think I was a lot more uncomfortable than he was. He's made great progress," she said.

Acosta's mom, Kimberly Acosta, said this year's festival is her son's first — "and probably not his last."

During a rehearsal last week at the Waikiki bandstand, Nicholas kept up with the pace of the corps of young strummers, playing a couple of tunes including "Supercalifragilisticexpialidocious."

Nicholas said his favorite uke tune is the lightning-fast "Noho Paipai" ("Rocking Chair"), which requires nimble-fingered chord changes.

And his uke idol? "Iz," he beamed, referring to Israel Kamakawiwo'ole. Nicholas is too young to have seen the iconic entertainer who died in 1997, but he's inspired by Kamakawiwo'ole's recordings.

And what about that other uke whiz Jake Shimabukuro?

"Who's that?" Nicholas asked.

Reach Wayne Harada at wharada@honoluluadvertiser.com.