M_Nagaiisawa said: ...Actually, this would make a lot of sense.
I thought this almost immediately:
I knew it wasn't Siren because everyone in the cast, good guys and bad guys alike, thought it was 'obviously' Siren and the first guesses made by the cast are never right unless those guesses are immediately dismissed by everyone else.
Queen Aphrodite doesn't make any sense. Not only is Muse is shorter than her and has a much smaller chest (Aphrodite is easily the most stacked Pretty Cure character I have ever seen), but it makes no sense for her to hide her identity.
No one else we've seen regularly makes any sense (as none of them would have any reason to hide their identities) except...
Ako was introduced for seemingly no reason at all as a friend/possible crush for Hibiki's little brother, but she keeps showing up and she acts all haughty towards the two main girls, even looking down on them somewhat, much like Muse does. Muse never speaks personally and always has her Fairy Tone speak for her, which makes no sense unless her voice would give away her identity, which means it has to be someone we all know and whose voice we would easily recognize. Finally, her costume covers almost her entire body, unlike normal Cures. Why? Either because she has stilts/extensions or some other sort of magical disguise to make her apeear larger than she is (and that would be obviosu if she wasn't covered up), or because, as a little kid who takes herself way too seriously, she's much more concious of her body than the older Cures are.