Are there nonstop flights from Siem Reap (SAI) to Tokyo (HND)?

No. The fastest connection is via Da Nang, about 6h 6m of total flying time.

What is the fastest connection from Siem Reap (SAI) to Tokyo (HND)?

via Da Nang ≈ 6h 6m, via Shenzhen ≈ 6h 6m, via Hanoi ≈ 6h 21m (estimated flying time, excluding layovers).

from 19,000 ANA miles (economy, one way, based on the published award charts).

Siem Reap-Angkor International Airport (SAI) to Tokyo Haneda International Airport (HND)・4,324 km

No nonstop flights. The fastest connection is via Da Nang (DAD), about 6h 6m of flying time (layover not included).

With milesANA 19,000 miles+ (via BKK)Economy, one way, estimate. Tap a connection for miles by cabin.

None.

7 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.