I spent a month in Japan a few years ago. 3 weeks in Kanto (Tokyo, etc.) 1 in Kansai (Osaka/Kobe.) If anyone has specific questions I might be able to answer them.
What are the things I absolutely can't miss while I'm in Tokyo?
#1 Japanese Parfait
If you do nothing else during your stay, have parfait. Japanese parfait is the most delicious dessert on the planet. Ideally, go to a dedicated parfait shop. But if you can't find one...even a random cafe at the airport will have parfait better than anything you'll find in the US. Get something big and decadent, with so many fruits and candies and chocolates hanging off the glass that you have eat your way to get to parfait. Japanese parfait is awesome.
#2 Vending machines.
You'll end up doing this whether or not anyone tells you to, but it's worth mentioning. There's some seriously neat stuff going on in vending machines. Experiment, and you'll probably find some drinks that are so tasty that you'll still miss them years later because drinks in the US are comparatively tasteless.. (alas...unknown citrus drink with a kanji name that I never identified, oh how I miss you.)
Also, there are things in Japanese vending machines that you don't see here in the US. Like beer. Live crabs.
#3 Sushi
Japanese sushi is better than US sushi. I assume it's because the sea-to-market process is more direct. Everything is more fresh.
Really...food of any kind is one of the best things about Japan. They just do some things better than we do. Food is one of them. I highly recommend that you go off the beaten path and eat at places where real japanese people eat. You don't have to stay in Roppongi your entire trip. Eat at hole in the wall one-man noodle shops. Eat at restaurants on the top floor of department stores. Eat in subways. Have a hot meal from a vending machine. Explore and try things. When it comes to food in Japan, I've found there to be an extremely casual relationship between price and classiness of location, and quality of food and experience. There are places where you can buy a $2 meal from a guy whose clothes look like he only owns the shirt he's wearing and have it way better than the $100 meal at a formal, high end restaurant. And incidentally, the formal, high end restaurant might not have chairs whereas the $2 hole in the wall does. I'm not saying that cheap food is better. Sometimes it is awful. I recall a street vendor in Ikebukuro selling "meat on a stick" that upon eating I immediately suspected it had been sitting there for days. The thing, there doesn't seem to be any easy way to tell you where the good and bad food are. Appearances can be very deceiving in Japan. But I can tell you that if you only eat in touristy places with menus in english, you'll miss out on a
lot of good things.
Things that aren't "absolutely can't miss" but I do nevertheless recommend:
* Go to Shinjuku at night. Walk around.
* To to Shibuya during the day. While you're there, go see Hachiko. It's kind of heartwarming. Also a good place to meet a date if you can arrange one.
* If you go to a shrine or temple...and not that it's essential, but they seem to be one things that a lot of people do...you may as well go to a Shinto shrine and pay the 1000 yen or so to have an ofuda made with Sailor Mars' demon banishing charm: "akuryo taisan."
Things that everyone will tell you to do, but that aren't that great:
* Hostess clubs
* The bullet train
* Tea ceremonies
* Hot springs
* Ryokan
* Karaoke. Only do this if you meet people to go with. Japanese karaoke is a social event in a private room. Not something you do at a bar like it is in the US.
A couple tips that will make your life easier:
EDIT: I just noticed that you specified you'd only be there for three days. Ignore the stuff about the subways. It will take a day just to learn how to use them. You don't want to spend a third of your trip being lost and angry.
* Be aware that "Tokyo" is like New York. There is a New York state, and a New York city. It's possible to spend your entire trip in "Tokyo prefecture" without ever once setting foot in "Tokyo city." But people rarely make the distinction in common speech.
*
Before you go acquire a tokyo subway map that has -~=BOTH=~- english and japanese station names on it. Very few are like this. Most have either only english or only japanese. The problem is that the stations names themselves are in kanji. So, if somebody tells you to take the Marunouchi line to Shinjuku stations...when you get there the names will be in kanji so you can't read them. Whereas, if you get a map in kanji you can visually compare characters to match them up even if you can't actually read them, but you won't be able to identify that a station is actually the one you want. Get a map with both.
* Even if you do the above, learning to use the subways is non-trivial. It is very much worthwhile if you'll be staying for at least a couple weeks. But don't expect to show up and immediately be able to get where you want to go. It might take 4 hours of being lost and going in circles before you're comfortable getting around. If you're not going to pay for taxis, be prepared to invest some time learning how to use the subway.
* The trains STOP MAKING PICKUPS AT MIDNIGHT. If you're out past that, they don't start again until 5am. It's a long wait.
* A western style hotel will cost $200/night in some places. A hostel will cost closer to $400/month. Even if you're only there for two weeks, it's cheaper to stay at a hostel. Also....
very significantly, hostels will have people at them who've been in Japan longer than you have, and know more about the best places to see and eat. They're also likely to know how to get there quickly and painlessly. Hostels are good places to make friends who speak english and can make your life easier and keep you from feeling isolated.
* Unless you already speak japanese
well, don't invest too much time trying to learn "a few phrases" before you go. Random japense will speak english better than you speak japanese. But...they're
totally embarrased about doing it. If you know 10 words in japanese and they know 200 words in english, they'll often try to use japanese anyway so as to avoid the embarrassment of speaking english poorly. If you don't let them know that you speak any japanese at all, this can generally be avoided. As to basic expressions like please, thank you, etc. everyone in japan knows these expressions in english. Don't worry about it. Personally I went to Japan having taken a semester long college course and spent a month with Pimsleur CDs. It was
way easier to function when I stopped bothering to try to speak japanese.
* If anyone invites you to a concert, I advise you to politely decline. Or at least be aware of what you're getting into. Music concerts in japan tend to not be sit-down affairs. They are interactive. Every song has a dance that goes with it, and everyone in the audience probably knows every dance for every song. Except you. Your choices will be to either stand (to see the stage over the people standing in front of you) and try to learn the dances (they have instructional videos that play during the concert) or stand there as the only one not dancing. Or sit and spend the entire time looking at someone's back.
* If you want to date while you're there you'll need 1) a japanese friend. Try craigslist or a penpal site. Start corresponding before you go. Don't try to meet girls on your own once you're there. It's difficult. But if you meet up with a penpal, they're likely to have half a dozen friends who'd love to spend time with a foreigner. 2) A cellphone. You can get them at any 7-11, but they require a residential address. Your friend can help you with this. Incidentally, be aware that "dating" in japan is very much less formal than it tends to be in the US. She will probably expect to pay half, and there's much less social stigma involved. Going on a date with a girl you've been introduced to via one of her friends is...from her point of view...much less intimidating than if you sit next to her on a train and politely ask her the name of the next stop.
used panty machines
Pretty sure those were made illegal a few years back.
Stay in one of those pod-hotels while you're there?
do they exist in Japan right now, though?
Yes. Try Narita airport. That's probably where you'll be flying in. However...just one opinion: sure, it's novel, but this is something you can probably pass on.
Stripclubs
...ok...but an important distinction needs to be made. A strip club and a
hostess club are totally different things. Hostess clubs you can totally pass on. At a hostess club, basically you'll pay $100 or so to sit on a couch with a moderately attractive girl who's uncomfortable if you touch her, all while paying $10-$20 for drinks that are cheap and awful. And if you don't keep buying them every 5 or 10 minutes or so they'll start hinting that it's time for you to leave.
If you want a club, go to Vegas. Some things Japan does better than we do. This is not one of them.
crossdressing
...not sure how else to phrase this...but there are some Japanese guys who are so pretty...honestly, I recall thinking once or twice that I didn't feel gay for finding them attractive. These were not crossdressers. These were guys walking around in clothes that they probably thought of as being manly. I'm not sure how to else to explain it. It's kind of like that famous german boy who got a sex change at age 15. He/she/it is pretty. And looking at "her" you know that she was male. Doesn't change the fact that she's pretty. In Japan there are some guys who are
not transvestites, have not had sex changes, aren't wearing dresses, and aren't attracted to men at all. Nevertheless, they are pretty. If one of those guys were to deliberately try to look like a girl...there's no way you'd know.
Go to Harajuku district and see if they actually do dress like that.
They do. Go on a weekend.
you could go to the Geisha district.
...this is also something you can probably skip. Unless you really want to pay $100 to watch 80 year old women in face paint pour tea slowly.