IJ 834 then K4 218 at Narita
Sapporo → Tokyo → Seoul
Timetable, Tokyo time
10:55IJ 834 from Sapporo at the gate
11:31K4 218 to Seoul leaves the gate
36 min apart on the timetable
The last days
IJ 834 and K4 218 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.