The tragic, ironic, and, honestly, funny, thing about the movie Babel is that much like the tower of the same name from the biblical story, the entire thing comes crashing down without remorse or pity. While in the biblical story the tower comes crashing down because God decided that people should have limitations, the movie comes crashing down because it takes itself so seriously and puts forth a moderately ridiculous story with only vaguely related, and often completely unbelievable, story lines.
In brief, the story follows the effects on several different families when two boys decide to play with a rifle and happen to shoot an American tourist in Morocco (played by Cate Blanchett, with Brad Pitt as her husband). This creates an international incident and sparks an overly-thorough investigation by the police in an attempt to prevent any thoughts by the Americans that Morocco may be soft on terrorists and terrorism.
The various stories in play here include: that of the American couple, Susan and Richard; the Moroccan family of the boy that shot Susan; Susan and Richard’s children and nanny (Amelia) back in North America; and a Japanese father (Yasujiro) and daughter (Chieko).
This last story line has virtually nothing to do with the rest of the movie. It just so happens that Yasujiro is a hunter and at some point in the past went hunting in Morocco and gave the rifle that was used to shoot Susan to his guide, who in turn sold it to the father of the boys. Nothing that happens to Yasujiro and Chieko throughout the story has anything to do with the rifle, except for two police officers visiting the family and Chieko trying to sleep with one of them (a minor point in their tale). The fact that Yasujiro is a hunter is irrelevant, the fact that he went to Morocco is irrelevant, his entire presence in the movie is irrelevant. But what’s worse than that is that the story isn’t even his, it’s his daughter’s.
Chieko, is a deaf-mute, is depressed due to her mother’s suicide, and desperately wants to lose her virginity. The story entirely revolves around her attempts to sleep with people and find comfort. It has nothing to do with the shooting of Susan and can’t really even be related back to it. Why is this story included? Probably because it makes the entire thing more international.