either view bots to make the video seem more successful or the label playing the video as pre-roll advertisement.
both methods are extensively used to push the stats of songs, though I don't know how much the Japanese do it. I'm not saying that it 100% is bots or pre-roll ads increasing the count, but that's always a possibility.
there's also the possibility that all the Furi oshis decided to play it over and over again (Furi seemed pretty disappointed and sad about the bad performance of honeymoon, judging by the tweets and videos from around the release time, so maybe the few fans who actually bought honeymoon try to compensate for the disappointing start, idk).
comments are normally one of the best ways to judge if a video is actually watched by an actual audience, but it also heavily depends on the channel and its viewers. half the views but 10 times less comments compared to City is certainly in the strange /questionable range. But it could also be the case that City is the outlier.
sometimes videos might also see a natural spike in interest for whatever reason. for example if a music video is released but a month later the song is used as an op or ed, you'll see a spike in views after one month.
anyway, last time I checked honeymoon didn't even make it into the oricon charts so it must have sold horrible. :/