Are there nonstop flights from Oita (OIT) to Hanoi (HAN)?

No. The fastest connection is via Taipei, about 4h 32m of total flying time.

What is the fastest connection from Oita (OIT) to Hanoi (HAN)?

via Taipei ≈ 4h 32m, via Seoul ≈ 4h 55m, via Nagoya ≈ 5h 34m (estimated flying time, excluding layovers).

from 23,000 JAL miles (economy, one way, based on the published award charts).

Oita Airport (OIT) to Noi Bai International Airport (HAN)・2,889 km

No nonstop flights. The fastest connection is via Taipei (TPE), about 4h 32m of flying time (layover not included).

With milesJAL 23,000 miles+ (via ICN)Economy, one way, estimate. Tap a connection for miles by cabin.

None.

5 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.