Is it just me or has Hino-san become the title on Dynasty that currently gets the most community engagement in terms of forum posts and involvement per chapter?
Sure, it's been going for a few years and has 92 chapters now, but 3600+ posts in the thread is nothing to sneeze at. Not even Futaribeya or Hana ni Arashi have as many posts, though then again Bloom into You has more than twice as many :D The power of having an anime adaptation I guess?
YagaKimi had tons of posts long before the anime was a thing. Long-runners are almost by definition popular, and those get a lot of posts. Series that attract the different combinations of post types of course get the most, like:
Approval/disapproval posts: “So cute!”/“This sucks!”
Plot predictions: “The ex will come back!”/“MC will confess in the onsen chapter!”
Plot theories: “They’re really twins!”/“That cough means the MC has an incurable disease!”
Shipping wars/off-brand ships: “SejuxSumin 4evah!”/“Sayaka is best girl!”
Critical debates/Interpretive readings: “You call it slow, I call it nuanced!”/“Anyone notice the two dozen shots of the various characters’ shoes?”
Tagging wars: “Subtext!”/“Yuri!”/“Subtext!/“Yuri!” (Lather, rinse, repeat).
Morality debates/real-life lessons: “Can head patting be sexual assault?”/“Is thirteen months an age gap?”/“Here’s how this relates to my experience.”
Comparisons with other series/anime adaptation(s).
Out-of-text issues: publisher behavior/how to access and pay for the online official version/mangaka career discussions, etc.
My impression is that the bulk of the posts for this series are “approvals” and “predictions,” meaning the total is a lot of posts for a series without many complex plot points/mysteries or very much actual controversy among the readers.