Recently, Michishige Sayumi of Morning Musume has been getting some bad comments because she follows other idol groups. Other idol groups that aren't in Hello!Project and are arguably Morning Musume's rivals; that's right, she's a fan of AKB48 (and Idoling!, too).
This is audio of Sayu singing AKB48's latest single, Ponytail to Shushu, to herself before a performance of Morning Musume's newest stage show, Fashionable. And it's been controversial.
Personally, I don't get it. The way I see it, fans are jealous because AKB48 is so much more popular than H!P and they lash out that an H!P idol would support AKB48. Because, really, AKB48 members are fans of idols too, and they don't seem to come under fire.
My favorite AKB48 member, Oota Aika, has mentioned that she likes S/Mileage and Yume Miru 15sai in her blog posts. Sashihara Rino is an unapologetic wota who loves idols. Kashiwagi Yuki has worn a Hangry&Angry shirt. But, as far as I know, there aren't wota armies out to get THEM.
IMO, I LIKE that an idol likes other idols; it shows that they're still interested in the whole idol world and thus probably love what they do. AKB48 is the most popular idol group in years and I think is bringing back female idols into popularity; H!P fans should be happy for their successes.
I am a fan of both H!P and AKB48, so I could be a bit biased... but I just think it shouldn't be a big deal that a girl is a fan of something.