In the music video for their song “Nervous,” The Demos’ frontman Jay Milton sports a Big Star T-shirt underneath a black leather jacket. It’s the perfect synecdoche for this young Rochester, New York band — they’re a throwback to a simpler time when pop-rock radio ruled, with Alex Chilton as its king.

It’s February 2012, and The Demos are playing Rochester’s Bug Jar venue. Jay’s belts out “Nervous” behind the curtain of his long black hair, which matches his black Rickenbacker six-string. His counterpart, bassist, and band co-founder Cal Saunders furiously plucks his red bass (also a Rickenbacker) while he yells background “ahhs” into a vintage mic. Their stage demeanor is serious and determined, quite the opposite of what their music suggests. But Jay, Cal, and the rest of their band are committed to rocking the hell out of whatever back room they happen to be playing that particular night. Right now, they’re focused.

The Demos’ official MySpace, PureVolume, and ReverbNation pages label them as a power-pop act, and it’s true. Their songs pair poppy guitar arrangements with sunny melodies that take days to leave your head, but there’s a benevolent bite, too. Take the furious guitar strikes that open “Nervous,” one of the lead singles from their debut LP, Lovely, which dropped last May. They act as a nice foil to the dreamy repeated chorus lines: “If you want her/You shouldn’t tell her to leave!”

The smashing power-pop of “Nervous” brought the band some interesting attention in an email received one night last year. Japanese label Thistime Records contacted The Demos after listening to Lovely on their Bandcamp page and told them it would be a huge hit overseas — especially thanks to the impossibly catchy “Nervous.”

At home, Lovely came out on Rochester’s Young Lion of the West Recording Company, an independent label founded by the band and their producer. But after a few months of contract negotiations and talk with Thistime, Lovely was officially released in Japan, too, making The Demos international power-pop stars. In January, Thistime built a huge press kit for the release, including planting massive in-store displays and listening stations at Tower Records in Tokyo.

Then, three weeks later, Lovely sold out on its initial run.

“We kind of knew that it happened, but it was only from translating Japanese tweets and social network stuff into English,” Jay told me in the grungy basement of the Bug Jar the night of the show. When he talks, Jay looks down at this hands and talks through his thoughts. Cal, on the other hand, stays quiet, giving him some time to formulate exactly what he wants to say.

“It’s hard to tell what’s going on a lot of times because of the language difference,” Jay said. “The guy we talk to at our label speaks English pretty all right, but every once in a while, it’s like, ‘What the fuck are you trying to say?’”

That’s been the biggest issue about The Demos being “big” in Japan — the vast language barrier. The overseas release also contains an eight-page insert for the jewel case with Japanese liner notes, as well as lyrics for the entire tracklist in Japanese and English. From the little research Jay and Cal have done using Google to translate the tweets, it’s all praise. To make it less complicated, they’ve also made an effort to start learning the basics of the language.

“Neither of us can speak any yet,” Cal told me as we sit on a ladder. “I’ve been writing down different words, kind of the basics. I figure if I can learn like 21 words in any language that are the basics like ‘bathroom,’ ‘hotel,’ ‘cigarette,’ ‘marijuana’…then I can accomplish anything I want, and that’ll be good.”

Cal said he’s been having dreams about Japan, as if the only way he can even fathom what’s happening to The Demos overseas is to discover crumbs of meaning in his sleep. It’s a wild experience for a local band to remain lukewarm in the States while simultaneously exploding in Japan, so Jay and Cal are sometimes left dumbfounded.

“There’s no way to even gauge it because you don’t see it in front of you all the time,” Jay said. “Nobody recognizes you here, so who knows if you went to Tokyo, maybe people would flock to you.”

With the two of them, another guitarist, a drummer, a keyboardist, and sometimes a backup vocalist-slash-tambourineer, The Demos are quite the crew on stage. They’d like to play in Japan, but right now, it’s a matter of money. Still, if events keep unfolding in their favor, Jay said the band will definitely make the 14-hour trek to play some gigs.

In the meantime, they’re recording more music, playing more shows, and saving up for the big flight across the sea. They’ve released two videos for Lovely’s singles and hope to keep riding the wave of positive feedback they’ve received since the album dropped.

“I think if I could say one thing that I really think about the record,” Cal said, “is that it finally fills a niche that could manage to be filled a lot more often. There’s a lot of what goes into a Demos record, and we got the right blend, I think, on this one. We made something honest that we could also be proud of, which is always a good thing to do.”

Jay and Cal have been creating music together since high school, and now, eight years later, their power-pop perfection has found a comfy home inside listeners’ ears. The Demos are America’s newest cultural ambassadors overseas. There’s no escaping now. Like the song goes: If you want it, you shouldn’t tell it to leave.