The fan reaction, based on G+ comments, seems to be somewhat mixed. There's some fear that she'll graduate, there's some hesitance to accept it, and mostly people are just confused. I, however, 100% understand and support her decision. In fact, I had almost hoped she'd do this. While obviously we all want our favorites to keep rising and going as far as they can go, the reality is that most of them don't. They reach a peak, and then they drop. There are some who take that drop in stride, but in general, it's hard to watch when it happens. Some girls react very poorly and seem almost angry at their lower rank, which suggests she's mad at the fans who didn't vote more, and some just react with sadness, which I don't particularly enjoy seeing. There's a dozen different reasons why a girl could drop, but the it never feels good. I expected that Yuriya would be able to handle a drop, since she's come all the way from the back to get where she is, but if she's worried about how she might feel, then I admire her decision to withdraw and be satisfied with the fact that she did make it as high as she did. 48 is a pretty good number, after all.
I guess the Japanese fans feel weird about it because, I don't know, it's kind of expected that any 48G member will keep doing it forever until they feel like graduating. So there's the fear that she'll graduate, but also confusion because she did do well, and so it's expected that she would continue because it's part of the brand of her group. She's obviously thrilled that she's gotten as popular as she has and was able to rank, but I think she just enjoys being an idol, regardless. She hasn't changed anything she's done to promote herself between when she first started and now, and she loves performing. While the election is the pinnacle in idol drama, it's also incredibly taxing on just about everyone involved, and maybe she would rather find it to be an enjoyable event to watch, as she always has when she didn't rank, rather than something she feels worried about. There's also something to be said for having such an important accomplishment be kept in the past to make it more special. Her dropping in rank wouldn't change her previous rank, but it might cheapen the memory a bit for her, to go so far and to fall. She seems to have thought about this a lot, and so I give a slow clap to her for making this very difficult decision.
Now, if she does graduate, that will be very sad since I never got to meet her, but she's accomplished far more in her career in HKT than I ever expected her to, she shouldn't leave with any regrets, and I support her no matter what.