He doesn't have to! Japan is close to Korea and the Pings should be fine for Online Games also he will get paid pretty well so he can afford to stay in both countries!
Japanese val players are paid way more than Koreans. Valorant is very big in Japan compared to Korea where only 1% people are val players. So it would be a dumb decision for seoldam to move to a korean team
Dude people in Korea and Japan would donate their livers to be part of VS! They are one of the biggest canditates that might win the highest Prize Money while NTH and whatever overrated japanese teams will never see a Champions or Masters Final!