astarte952 said: is she really 17 years old? for me she looks in the last picture much older.
It's a "women are sensitive about their age" joke. For example, Kikuko Inoue, a prominent seiyuu, always describes herself as "17 and XXXX days old," even though she's 48(in her case it's probably a self-conscious running gag for her, I'm guessing). 17 is usually the cutoff age that gets used for this in japan.
Ai-chan is Marie Ange after reincarnating herself in the egg from episode 8. It's probable that Marie Ange looked like Ai-chan when she was originally born.
