Got two random questions.
Why do Japanese fans seem to be so crazy about Ton-chan? She seems to have a pretty huge fanbase among Japanese Idoling!!! fans, from everything I've observed. I don't dislike her at all, though she's not really a favorite, she's more of a middle-tier member for me in some ways, maybe like the highest member in the mid-tier. Any ideas? Is there something I'm missing about her or is it just one of those things where she has some major trait that's way more popular with Japanese folks?
I see that you have answered your own question below by saying she has the looks and can sing, let me add a little more on that. I would describe Tonchan as "the girl next-door" type where she is seen as a normal person who still has traditional traits of an ordinary girl instead of having a very eccentric character. While she's still an idol, she also exhibits being an introvert, thereby retaining the feminine quality that most Idoling members simply don't have. Even Rurika doesn't really have that feminine quality by comparison to Tonchan, and that factor probably counts a lot towards those who prefer that in an idol, and there are many in Japan who like their idols to be normal rather than different, as it helps in fantasizing during hand-shake events and imagining that Tonchan is their girlfriend.
Another factor is that Tonchan is very well-known for being "majime" as well as being book-smart, which are extra-bonus points and almost a royalty status in terms of idol industry. Female idols in general are far above average in looks, but not necessarily ideal in terms of being an ideal bride candidate from their other short-comings, however Tonchan has the best of both worlds as her "majime" and intelligence projects very well as a dedicated wife and a caring mother down the road. Being "majime" also gives the jealous fans a peace of mind that she isn't going out and having a wild night with her college buddies. In short, she still has that pure quality that most women in her age don't, in that sense, she's a classic "hakoiri-musume" (A girl being raised without any outside influence, and remaining as pure as possible before getting married.), add to the fact that she's also an idol makes her irresistible to the opposite gender, it's like a woman who has a serious job like a lawyer, but drop-dead gorgeous like a supermodel, you know what I mean?
There's another layer to Tonchan's attractiveness, after what I've said about Tonchan it would be easy to assume that she's very girly, but the thing is she's also athletic. When you watch the Olympics you come across very good-looking female athletes once in a while, imagine that they are also highly intelligent, have a good head above their shoulders, and a pop star, that's what Tonchan essentially is. Basically Tonchan has a lot of ギャップ qualities about her that makes her very appealing, I mean she is rather petite in figure and you wouldn't think she has big breasts at first glance, but she has fabulous melons to be reckoned with, unexpected "gaps" like that really raise an idol to the next tier.
So after what I've said about Tonchan I should be the biggest Tonchan fan but I'm not, because while Tonchan is not ugly by any stretch of imagination, her looks is not what I find the most appealing, there are quite a few other female celebrities I would pick before I would name Tonchan in terms of looks to be honest, but that's just my personal taste speaking and not a diss at Tonchan. Secondly, her personality is too girly for my liking, I prefer an ideal woman of my desire to be a little bit more outgoing and have some sense of humor. If I was with Tonchan I would worry all the time about pleasing her and trying not to upset her on something, that gets tiresome.