
choose? a stranger old man over his sister jinah? is that even a question i'm confused

It's not to choose between the old man and the sister, but rather he has to choose whether he will give the cure to him or not since they only met for the first time even though he is the father of his guild teammate, and whether he has to choose between going to save Japan or stay in Korea to take care of the unstable mental health of his sister.
baby oh noo oof i hope keith doesn't react badly im gonna cry my baby :(((