Is my friend eligible for the TWOV?

So a friend and i have a flight from US to South korea with a 19 hrs layover in shanghai so i know we are eligible however we have another friend that will be in japan with family and is supposed to be meeting us in shanghai and flying to south korea with us. However i believe she has separate tickets, so my friend has one ticket from US to Japan and a separate one of Japan to Shanghai and a ticket to shanghai to South korea, so since her flights arent really considered connecting flights we are wondering if she is still eligible and we have no idea have to get more information...