Question: what should I know about hosting a japanese exchange student? 

Answer: I'd like to add some things. When they give a gift, it is not wholly altruistic, they like to cancel their "debt" to you (in this case by being offered a place to stay). Also don't bother bowing to them because there are tons of different nuances to the bowing ritual that American's wouldn't understand unless they were taught it from a young age. In other words, you're bound to do it wrong. Other than that, my experience with Japanese people has always been positive. They were eager to learn English and were very kind and polite.
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