"We just banged on some shit, and we worked it out," Islands frontman Nick Thorburn (formerly of the Unicorns) says of his newest collaborative project, Mister Heavenly. With Ryan Kattner of indie cult favorite Man Man and Joe Plummer of Modest Mouse and the Shins on drums, in addition to Thorburn, Mister Heavenly joins the Gutter Twins and the Postal Service as the latest supergroup project to appear on Sub Pop when its full-length LP, "Out of Love," arrives Aug. 16.

Video: Mister Heavenly performs "Pineapple Girl"

According to Thorburn, the project started last year when Plummer, who had a friend in Sub Pop head of A&R Tony Kiewel, sent over what Thorburn calls a "murky, janky little cassette-tape demo." A cassette? Really? "You know what? I don't know why I said that. It wasn't on cassette," Thorburn says with a laugh. "I'm mythologizing."

Not that this new "doom-wop" group needs a myth: Cassette or not, what started as a half-baked demo has since translated into two singles, "Mister Heavenly" and "Bronx Sniper" (both given away for free online), and nearly a year of high-profile West Coast tour dates.

Kiewel, who's also responsible for Sub Pop's deal with the Postal Service, says that one of his primary attractions to Mister Heavenly was the collaboration's aesthetic similarities to its supergroup predecessors.

"I'm really struck by the parallels," Kiewel says of Mister Heavenly and the Postal Service, the Death Cab for Cutie/Dntel collaboration. "[The Postal Service was] unabashed about [their New Order influences] and that's what these guys are now doing with doo-wop."

Kattner and Thorburn--both the primary songwriters for their respective groups -- agree that the collaborative process has been a welcome change of pace. "Coming out of the Man Man stuff, I was so burnt out that I needed something else," Kattner says. "It was really refreshing to hit a part of a song and [be able to] just pass it off."

Though the last projects from Islands and Man Man fell drastically short of expectations (both Islands' "Vapors," released in 2009, and Man Man's "Life Fantastic," released in 2011, sold fewer than 10,000 copies, down at least half from both bands' previous records, according to Nielsen SoundScan), Mister Heavenly has developed substantial buzz since it joined Sub Pop last November.

Certainly, part of the excitement came with the addition of high-profile touring bassist Michael Cera. The indie-film leading man joined the group on many of its 2011 dates, which included headlining shows and performances in support of electro-pop act Passion Pit. The addition, as Thorburn tells it, was a happy accident: After seeing Cera's performance in Scott Pilgrim Vs. the World, Thorburn and Kattner called the star, who plays bass in the movie and whom Thorburn had met while attending a benefit for author Dave Eggers' literary nonprofit 826.

Video: Mister Heavenly During Their Tour With Michael Cera

Though Cera will not be joining the Heavenly crew on their upcoming fall tour due to prior filming commitments, it's connections like these that Kiewel calls the band's greatest asset. "[They have an] incredibly deep pool of ideas and contacts [that they've] accumulated in their various other projects over the years," Kiewel says. "They have ideas about photography, graphic design, illustrators, video-makers and pretty much everything else you can think of."

Early buzz has translated into early sales -- more than 400 presale orders were placed within the first 24 hours after being announced. That's exactly where Sub Pop wants this release, Kiewel says, noting that the band's 6,000 Facebook fans are "unprecedented... to see with an artist with no physical releases under its belt."

And while the trio has agreed that its main projects take precedence over this collaboration, Thorburn promises that Mister Heavenly is no bro-jam band. "It's not just, like, a one-and-done, throwaway kind of thing," he says. "I've got Islands ready to go, but if Mister Heavenly works... If it was something the masses wanted, demanded, I will give it. I'm basically on call."