It definitely seems a little odd: middle-aged men who are obsessive fans of teeny-bopper bands.

But in South Korea, there's a group of men in their late 30s and 40s who are crazy for the K-pop girl group, Crayon Pop.

Jung Jong-hun is one of these obsessive fans. He seems pretty excited when he shows me a video on his smartphone. It’s of him, and other men like him, singing and dancing at a Crayon Pop concert. Not only do these guys know all the lyrics and moves, they’re also dressed up like the five singers, who are all women in their 20s.

In the video, Jung is wearing sneakers, a red tracksuit embroidered with his nickname, and a white construction helmet with a strip of red electrical tape on it. From his point of view, it’s no different than going to a baseball game and wearing your favorite team’s jersey.

Jung says he’s not embarrassed by his love of K Pop girl groups, and he says there’s a whole online community of men who feel the same way.

Okay, so it's no surprise that older men are attracted to younger women. But Mark Russell, author of the new book "K-Pop Now," says there are other reasons middle-aged Korean men — and women — like these songs. It’s partly the economics of the music industry here.

“Korea doesn’t have a very diverse music market at the mainstream level," Russell says. "Most of the money is in today’s music; that’s where the record companies put their energy. It's what you are going to encounter. It’s the music of now that’s in the public consciousness.”

But the borderline obsession that some Korean men of a certain age have with Crayon Pop goes deeper than that.

In Seoul, there's a media art exhibition under way that features a video of about 50 middle-aged men chanting the names of the singers in the group. All of the men are wearing the signature work-out clothes. They've all been supporters of these musicians since they started out as street performers.

“One of the guys told me he keeps his trainers and helmet in his car trunk because he doesn’t want his wife to know about it,” says Jung Yeon-doo, who created this exhibit.

He says the Crayon Pop group may not be the prettiest or most talented K-pop performers out there, but they give off the impression that they’ve worked really hard to achieve success — and that strikes a chord with these older Korean men.

“They get a feeling of healing from these girl groups. Being successful is hard. When you graduate from school, you have dreams to be something, but when you get older, not many people achieve what they want to be. If you see someone with strong desire trying to be successful and showing that passion, it moves people,” he says.

Jung Jong-hun, the Crayon Pop fan, says that’s what got him hooked.

"I think these singers in Crayon Pop are working really hard, maybe harder than other groups," he says. "I knew how that felt when I was in my 20s."

That hard work seems to be paying off. Crayon Pop is sheduled to open for Lady Gaga on her North American tour this summer. Though Jung says he’s not so sure American men will feel the same way about the girls as he does.