NH 8421 then WE 504 at Narita
Chicago → Tokyo → Seoul
Timetable, Tokyo time
18:38NH 8421 from Chicago at the gate
15:05WE 504 to Seoul leaves the gate
20 h 27 apart on the timetable, overnight
WE 504 leaves 20 h 27 after NH 8421 arrives on the timetable: more than half a day, so not a connection we count.