When I went to see a Morning Musume '14 concert last year in New York, I asked some of their enthusiastic fans when and how they came to like the idol group. Many of them said they learned about the group around 2006 on the Internet.
There is a programme on YouTube titled "Hello! Project Station" (Halo! Sute), featuring Morning Musume and other female idols who belong to the same Hello! Project agency.
Popular both at home and abroad, the programme started in February 2013 and is updated each week. New videos have been posted more than 100 times.
Without a doubt, the Internet contributed to Japanese idol groups becoming known around the world.
To learn how idols feel about the phenomenon, I interviewed Maimi Yajima, the leader of idol group C-ute and the Hello! Project, and Mizuki Fukumura, the leader of Morning Musume '15.
Fukumura, an enthusiastic fan of the Hello! Project since she was young, said she never failed to view an online site that was a forerunner of "Hello! Project Station."
The streaming programme started in 2006 - just around the time when Morning Musume was recognised by people around the world.
It is symbolic of how the broadband Internet access made available around that time drastically changed the system of providing entertainment content.
What can be called "the second Japonism" spread Japan's pop culture, such as anime, music and fashion, across the world via the Internet.
"When appearing in 'Hello! Project Station' I keep in mind that people outside Japan are also watching the programme. So I talk about and explain things that don't seem special to us," Yajima said.
"I call members not by their nicknames, but like 'Mizuki Fukumura of Morning Musume '15.' I also try not to speak too fast."
I heard from their fans in New York that in the United States, idol fans usually can speak Japanese better than anime fans because many Japanese anime are dubbed into English.
But "Hello! Project Station" and similar programs and blogs written by idols are usually provided only in Japanese. So their fans need to learn Japanese to understand and enjoy them.
The situation is completely different from that in China and Taiwan, where many people want to see anime in the original Japanese and therefore have pretty good listening skills, even if they can't speak it well.
Both cases indicate that online programs and blogs of idols serve as important learning materials for Japanese.
I also want to point out that idols don't separate overseas fans from Japanese fans in their mind. Yajima said, "I just want to present how Japan is now and how we are now [to the audience]."
Fukumura also said: "I don't separate them. For me, they all are fans of Hello! Project and see us with great interest."
Their fans overseas want to have the same fun experience as Japanese fans. Idols are keenly aware of this.
When I give lectures overseas on Japanese pop culture, I often bring video letters from Morning Musume with me.
When I show them to the audience, they look so happy! People on this planet can share the same sense of values beyond borders by having something they like in common.
"When I saw a video of people around the world singing a song by Morning Musume in turn like a relay, I felt like Morning Musume was uniting the world," Fukumura said. "I was so happy about it."
So how do they want to be active in this Internet age?
"Our basic work is giving concerts," Yajima said. "When we broadcast our concerts on the Internet in the past, I was surprised to find out that people across the world were watching. I hope this happens more."
Fukumura said: "We realised we had many fans overseas when we went abroad. I want our Japanese fans to learn about our fans elsewhere in the world by seeing our online videos."
Idols are the living creators of a valuable culture. Idol culture is unique and expanding across the world via the Internet.