I did too, but I really noticed that the quality of the story went down after the Noah invasion arc, which I think was the climax of the series. It's a shame what happened to the author, unlike Kubo and Kishi, it was kinda out of her control, with the arthritis and plagiarism lawsuits.
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I like the whole series, but it did feel like something was "pulled out" when they revealed that it wasn't a game after all, just a test of sorts. And then there's the "aliens behind the whole thing" reveal and the ending was rushed. Yeah I guess it doesn't belong on the list, it was not bad but also not even close to OP tier either.
I checked out the D. Gray Man thread and someone said since they said it got pulled from the magazine it was basically cancelled. What exactly did she plagiarize anyway?