Correct. The girl doesn't like doing her own dirty work so she put a spycamer/audio device in the fan and had her brother dress up to look like her and go to the festival in her place. And then took Chiharu's little sister (who may or may not have the same genetic thing going on based on how often she has to go make hospital visits since it's not explained yet @_@). Also the younger brother probably feels pressured into doing all of this by his family and by his older sister because of how fucked up the world is at the moment and how he had grown up he was probably told to put more importance on whatever his sister wanted. (this is all speculation by the way)

So aside from REALLY having a fiance, he also has a meddlesome "brother"?
What is happening?!
Wait! Could this be the reason why Chiharu's so eager to impregnate Izumi?? To get out of his engagement?