The short answer is "not a lot." I did a bit of googling in Japanese, and the net take-home pay for most hotel jobs seems to be around 220,000 yen a month, or about $2,200 US. It isn't as bad as it might sound. Most of these folks are either working on a short-term basis (young guns fresh out of school with few liabilities) or have lifetime employment with full benefits, and many are getting a serious break on rent, either by living with family or by getting free/subsidized housing from their employer. So most of this income ends up being disposable.