Traditionally, Japan is the biggest field for Korea-based girl groups.
Blackpink is the first major act which escaped the Japanese trap, i.e most of their foreign activities confined in Japan where there is supposedly the most money involved. Ironically Twice is making some inroads in USA, but it might be too little, too late.
Some minor acts, like K.A.R.D. Dreamcatcher, Loona, Brave Girls, etc passed Japan and attacked United States and Europe directly, but for the larger companies the allure of Japan is simply great.
Out of the more prominent girl groups of the 4th Gen,
aespa, Kep1er, IVE and LeSserafim have Japanese members.
Gidle has no Japanese members but 3 Chinese-speaking members instead (Minnie is Chinese ethnically)
NMixx has one English speaking member, and NewJeans has 2 English speaking members (Ngoc Han barely speaks any Vietnamese).
So, it is quite probable that at least aespa, Kep1er (which was create to appeal to Japan to begin with), IVE and LeSserafim will spend a lot o their activities in Japan.
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It is ironic that the Covid thing confined the girl groups to K-O-R-E-A where they engaged in youtube and tiktok activities , extending their reach to the rest of world significantly.
Inside K-O-R-E-A, there is not much to be had. It only takes 10% of the world market for KPop, probably less. Plus it is significantly influenced by someone who is extremely hostile to KPop's worldwide expansion.
The 4th Gen has to be quick seizing the gap created by the end of BTS' height, but if they are bogged down in Japan, they lose the chance to claim the world for all.
I wish companies drop their immediate greed and aim these acts to seize the world when the afterglow of BTS is still there, but company execs tend to think about immediate profits and will probably make the wrong decision to send the girls to Japan for an extended time, losing the chance for maintaining the world conquest.