Def Tech’s Yuki “Micro” Nishimiya and Shenan “Shen” Brown greet me with an “Aloha” as I walk into their small office in Harajuku to discuss their 10th anniversary and new album, “Howzit!?”

The Hawaiian-Japanese duo was one of the country’s most well-known musical acts a decade ago, and they both seem as close as ever, but Micro tells me that if it hadn’t been for the birth of Shen’s baby daughter in 2009, Def Tech probably wouldn’t exist today.

“Our first album sold millions, bringing us fame and money,” Micro says, speaking confidently in English. “After that, our egos came out. We hadn’t necessarily changed, but the environment was different. There were cultural issues as well so we decided to split in 2007. I pursued a solo career, Shen went back to Hawaii and we had no contact for three years. Then I heard about his baby and tried to get in touch. The problem was his phone was always engaged!”

“Micro finally got hold of me when I was in the hospital,” Shen continues. “He came to visit and my wife casually asked us to sing a lullaby. At that moment we looked at each other and everything seemed to return. We were back in the studio the next day.”

Both men have released a lot of material in the five years since that lullaby reunion, however, neither managed to get back to the level they were at in the mid-2000s when songs such as “Catch the Wave” and “My Way” topped the charts. They’re now hoping “Howzit!?” will put them back in the limelight.

Inspired by the oceans of Japan and Hawaii, the new album has a chilled-out, summery vibe to it, particularly on the songs “Gone Surfin’ ” and “B-3.” The one exception is “One Day,” which is arguably the record’s standout track.

Shen describes “One Day” as being “a multifaceted piece of music that could be played at a wedding or a funeral.” It features Jake Shimabukuro — the renowned ukulele player who became a star in 2006 following his heartfelt rendition of “While My Guitar Gently Weeps” on YouTube.

“Jake played his part over the phone from his brother’s garden in Hawaii,” Shen says. “I had the iPhone out in front of me recording it and that was the version we used for the CD, so they’re real cars you hear in the background. With this LP we wanted to bring the sound of Hawaii to Tokyo and this song encapsulates that. I think it’s the strongest track on the album, Jake’s ukulele playing is amazing.”

Both men were also very complimentary about Jake’s brother Bruce Shimabukuro, describing him as “the captain,” who steered the album in the right direction. He played ukulele on “Gone Surfin’ (Jawaiian Version)” and Micro’s personal favorite “Fushigidane,” while former Ka’au Crater Boys frontman Ernie Cruz Jr. provided the delicate acoustic guitar sound on both of those songs.

“Ernie’s our mentor,” Shen says. “We were both into Ka’au Crater Boys when we were younger and in a sense they were one of the reasons we decided to start a band. I decided to drop out of college,which Micro says was his fault, while I blame myself for him not becoming a professional surfer.

“It was tough early on. We sent a demo tape out to ever major record label in the country, but were told each time something was missing.”

They decided to go down the independent route and were rewarded in 2005 when Def Tech’s eponymous debut soared to the top of the charts. It was the third biggest-selling album in Japan that year and led to an appearance at Live8 in Tokyo. Def Tech’s third album, “Catch the Wave” was also a huge commercial success, but it came at a price. Arguments tended to get out of hand, which led to a split in 2007. These days they have what Micro describes as “peaceful conflicts.”

“We fought a lot making this album,” he says. “Not just among ourselves, but also with the production team. The difference is that we now handle it much better. We don’t escape when things get heated. We can speak our minds more freely and this helps us creatively. We’ve matured over the years and that’s reflected in our music and what we wear. When we started everything was ‘x-large,’ now we’re comfortable with clothes that fit.”

The in-your-face attitude the pair had in those early years appears to have gone. They seem contented and more laid-back, but both men are determined to get back to the top in Japan as well as making an impression abroad.

“We want to make a splash internationally,” Shen says. “This is our first time to release material on iTunes in the U.S. and Japan at the same time. It’s both scary and exciting. It feels like we’ve come full circle and we’re back at the beginning. Our boards are ready and the wave is about to come.”

“Howzit!?” is in stores now. Def Tech will perform at Kawaguchiko Stellar Theater in Yamanashi Pref. on July 12 (5 p.m start; ¥5,800; 06-6947-1197); Blue Note Tokyo in Minato-ku on July 15 (7 p.m. and 9:45 p.m. starts; ¥8,500; 03-5485-0088); Billboard Live Osaka on July 16 (5:30 p.m. and 9:30 p.m. starts; ¥7,000-¥8,500; 06-6342-7722); and Osaka Castle’s Ongakudo on July 18 (5 p.m. start, ¥5,800; 06-6947-1197). For more information, visit www.deftech.jp.