Talk:Monster Musume: Everyday Life with Monster Girls Online/@comment-5791947-20160608100502/@comment-25390763-20160608113639

Could be a whisk to suggest cooking, or it may even be maraccas like suggested (though there's usually two and her other hand doesn't have one), but my bet is karaoke Miia with a microphone. Cooking Miia does sound just as possible, and that top looks like it may be an apron.