Asking "How are you?!" or anything personal in the job place here in Japan is.. well.. odd.. Of course each business place is different. But if you walk up to your Japanese associate and ask "genki?" don't be surprised if they look confused or take a while to answer.. the common answer is "chotto".. meaning "uhhhh" or "not so good".. This doesn't mean you should break your usual habits of greeting people with "How are you?".. but just be prepared for the response.. They will get used to it if you ask everyday!! smile, be yourself and noooo worries!!
On the train, Don't stand next to the "respectable looking but sleepy/swaying" business man . This may be hard to do, especially on a night train.. BUT keep an eye out!! There may be more than sleepiness to that sway.. I have personally dodged pee puddles and vomit.. Eeewww... not nice ways to end a day..