I was a fan in 2005 of Asian Pop - Mandopop, K-Pop, J-Pop
Back then, it was all Multiply, Livejournal, Soompi, etc but mainly LJ for both K-Pop and J-Pop needs.
In that era, JE (Johnny's Entertainment) was the JYP/SM/YG not only for J-Pop, but for Asian Pop fandom. You'll meet a lot of people into Mandopop or K-Pop but it was almost certain they were a JE fangirl stanning either KAT-TUN (who were massively popular EXO levels), NEWS, Yamapi, etc. Especially Kame, Jin, Yamapi those three had fandoms with a lot of impact.
Do you think JE missed a chance by not capitalizing their former monopoly on international fans and waited for K-Pop to scoop that market up? I know a lot will say "but J-Pop has a bigger market/earns more blah blah" but let's accept it, there was once a huge impact that's completely lost now. Back in the day fans pulled all kinds of stunts to score lottery concert tickets and Friday was the Dispatch of our time. Despite what people say, it's obvious JE has lost it's impact nowadays and is slowly becoming a shadow of it's former glory.