Psyren, Double Arts and if we're including "Indefinite Hiatus" then Iris Zero are all ones I go back to every now and then and think "What If?"
Manga
There’s so many manga that I wished had an ending, but Ultra Heaven is my answer. I read it probably about 10 years ago, and I still remember it from time to time. It was a really unique and trippy manga that I wish had an ending. I have no idea why it was cancelled though.
Another one that’s not officially cancelled is Vagabond, but I’m mentally prepared for it to have no ending since it hasn’t been continued in forever. From time to time, I’m just like “I wonder if it has an update?” The answer is always no.
Also enjoyed ultra heaven, you can't always tell if the visuals/frames are depicting reality or Kabu's mind or something in between. which leaves a lot of possibilities for where the story could go next (if it ever starts again rip)
It hasn't been years but I wonder what Yuuji Kaku could have done with Ayashimon were he given the chance to tell that story in full. It had no time in Jump to lay the groundwork, but the Yakuza Yokai setting oozed style.
Ginka and Glüna was another series that was taken from us before its time. I think it suffered by being a little more cartoonish and straight edge in its storytelling in a time when Jump readers seem to be into more dramatic and edgy themes.
HxH.
:'(
Hunter x Hunter isn't cancelled.
It hasn't been cancelled, but on the WSJ website, it's been moved from the "Serialised Works" section to the "Archived" section. I think that's about as much confirmation as we'll get.
Confirmation on what? Togashi still works on it, considering his possibilities due to health (his twitter). Manga just won't be serialized weekly anymore.
I'll be very happy if it continues, but I have no hope.