This series started out with such potential, but quickly lost its way.
In my eyes, there are two major flaws.
The first problem is the sudden and inexplicable change in the direction of plot.
A few chapters in and the mangaka throws us a curveball regarding Yuuki's true identity and the story derails, never to right itself again. Where the plot had, up to that point, been intriguing and well thought out, after that it falls apart. It turns into a convoluted mess of barely understandable politics and dispassionate relationships.
I'm not sure what prompted Hino to do the old bait and switch routine (dangling one type of story under our noses, just to replace it with something else) but it was the death of this series.
The second problem I had with VK was the lack of heart. I felt the beginning had a lot of it and I really connected to the characters and their plights. But along with the change in plot direction also came a change in focus. Where the characters used to shine and take center stage, the meandering, hole-filled plot took over. If the story had even been merely decent and executed well, this could be forgivable. But that is not the case.
Instead it feels like Hino just came up with random scenarios to play with the hearts of Zeki and Yume fans. The characters became but a shell of themselves, just soul-less vehicles for the pitiful excuse of a love triangle. None of the main characters stay true to the roles the mangaka originally gave them, but not because of development or growth, which would have been acceptable even if it was for the worse.
No, the tragedy of it is that Hino removed much of made these characters inherently them and turned them into boring, blank slates - one dimensional generic caricatures no longer able to touch their audience.
It grieves me to see how this series turned out, with so much wasted potential coupled with an unfulfilling ending. I can only hope, since previously she had been one of my favorite mangaka, that Hino's next series will be handled better.