Cube opened a Japanese LIGHTSUM twitter account, the only member of the foreign line, Hina, is Japanese, and one of the first things they're doing for pre-debut promotions is going on M-Net Japan's 'M-Tame Bang' in June. Their concept also appears to be very Japanese gp friendly.
It makes sense. G(I-DLE) is already pretty popular in China so moving on to a different music market would be smart. If this is the case would love to see LIGHTSUM put out some original Japanese songs later down the line.