Fifi
Tried this option if you take JAL as I took JAL in June and was really fast and convenitent for 轉機.
Took JAL flight from HK to Osaka (Kansai) at 10:05am, arrived at Osaka at 2:45pm, go through immigration and get your luggage, then take the flight at 4:05pm to Sapporo, then you arrive at Sapporo Chitose Airport at around 5:55pm, which was quicker than you transit in Narita Airport and clear customs is faster because the queue is much shorter than Tokyo Narita and more convenient...