ya this ia a specisl charter flight only
normally sq wont fly direct
Yup any direct, non stop flghts from SG to Chitose will be a special chartered flight from SQ.
JAL and ANA do offer such chartered flights ard Dec period too. Dec is a super busy period for airlines cos many pple wanted to go for snowy holidays in Hokkaido mah

Airlines won't create chartered flights if the demand is not there.
Rem, when your SQ flights touches down at Chitose, that plane (it was 777-300 last year) will bring similar number of Japs travllers back to SG. And the seats will be all taken up before the chartered flight can take even materialise