Continuity mistake: When the nanny is walking in the desert, she falls down. However, when she is on the ground, she is wearing shoes completely different than the ones she had been wearing the shot before.
Continuity mistake: When the father is trying to wrestle the rifle away from the son, the shot changes to the police running around frantically. If you look in the background you can see the the boy firing the rifle without the father. The shot changes again to the father wrestling with the boy for the gun.
Answer: Chieko was traumatized by her mother's death (and feels a great need for physical contact and affection) (though she (mistakenly) manifests this in a sexual way...not too unusual in young disabled people). Her father seems to suffer from this same horrific loss, which means that they're both stuck in a kind of "loss-limbo" (unable to satisfy either's needs). On the balcony, the two holding hands suggests the beginning of the "breaking of the ice" between them. BTW, her nudity-in that scene-has no significance. This is just a father and his child. I wish the movie-makers had given us a clue about that damned note. Though the secrecy of it does kind've suggest that it reflects her intent to end her life...even as her mother did. Her appearance in the nude to the cop (which, on the face of it, seems very erotic) challenges us to remember that people exist on "different levels" or expressions (or "ego-states"). The main thing is that she's calling out for affection and being comforted.