[Meat Pao]

I would think that it is indeed primarily cos of the reasons you mentioned, especially with half the album belonging to HEART STATION which already sold 1m+ copies so it probably didn't give fans much of an incentive.

I also think the new songs, which were a big selling point, weren't really that big hits — I would say Goodbye Happiness was only somewhat of a moderate hit? And Hymne a l'amour did get a tie-in but I think because it's not really a conventional pop song it didn't turn out to be a hit either. Considering Hikki's career stage by that point, I think it would have really taken only a mega hit (Flavor of Life for HEART STATION, Hanataba wo Kimi ni + comeback hype for Fantome) to yield big numbers because her sales no longer rely on her being the "it" girl that she was in the late 90s/early 2000s. So the result was probably the same reason why Hatsukoi didn't sell as much since it didn't yield big hits either (it still got #5 album of the year, but it still was a >50% drop tho).

And in terms of actual album promotion I don't think she actually did any, she probably went on only 1 or 2 music shows, if any at all (my memory is failing me, but I just remember that aside from the tie-ins there was virtually no promo for this album other than the typical billboards etc.).