While some groups debuted in another country successfully and at the same time, they keep their status in Korea, there are also groups that lost their status in Korea after they debuted in another country.
The first one is Wonder Girls. I believe that everyone is familiar with the girls’ hit song – Nobody. Because of the success of this song, the girls became the top girl group in 2008. And then, they started to prepare their debut in America. They cooperated with many America artists and they also had many songs in English version. However, because during that time K-POP was not as famous as nowadays, the girls’ hard working didn’t bring too much returns and because in 2009, girls groups boomed a lot and Girl’s Generation developed their status by Gee and Genie, when Wonder Girls came back in Korea, their status has already decreased a little bit.
The other example is Kara, which debuted in Japan in 2010. Kara raised their popularity by Mr. in 2009 and they chose this song as their debut song in Japan. it is a very successful debut in Japan and many fans support the girls. However, because they developed their Japanese career soon after they had popularity in Korea, they didn’t have the chance to strengthen their Korean popularity. The girls disbanded earlier this year but they are always going to be the legend of K-POP groups debuting in Japan.
In recent years, most of the groups debut or release at least one album in another country. However, there is one idol group that only releases Korean album but their popularity is worldwide – Sistar.
I think the reason why they have so many fans all over the world is because their songs are catchy and their songs are perfect for summer. When talking about summer, people always say it must be Sistar.