I think Akira is the Meniacal Girl, and I don’t think he knows that Maki-kun is Kari, otherwise “she” wouldn’t have freaked out about Kari taking “her” clothes off, or when she flashed her panties.
And here we have two instances of a guy turned girl. One of them fully embraces the transformation and considers himself a girl and the other still considers himself a male and gets flustered upon seeing panties.