Are there nonstop flights from Hakodate (HKD) to Seoul (ICN)?

Yes. Jeju Air fly this route. Flight time is about 2h 3m.

What is the fastest connection from Hakodate (HKD) to Seoul (ICN)?

via Sapporo ≈ 2h 49m, via Nagoya ≈ 3h 9m, via Tokyo ≈ 3h 14m (estimated flying time, excluding layovers).

from 7,500 ANA miles (economy, one way, based on the published award charts).

Hakodate Airport (HKD) to Incheon International Airport (ICN)・1,319 km

Nonstop flights available (1 airline). Flight time about 2h 3m. Nonstop return flights also operate.

With milesANA 7,500 miles+ (via NGO)Economy, one way, estimate. Tap a connection for miles by cabin.

4 one-stop options, sorted by estimated flying time. Tap one to see the airlines on each leg and booking links.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.