Things to do in Tokyo?

Tokyo is a big city and each "area" offer a different experience, I hope you have a JR pass or something equivalent in order to take the metro: the yamanote note is a circular line that will easily bring you in all those districts.

As far as what to do:
Akihabara: it's the electronic city where you can find lot of video games and anime goodies (BR, DVD, OST, Figures...), lot of arcades e.g. there is a Sega and a Namco tower, maid cafés to live the Otaku life once in your lifetime, lot of sex shops and eroge material also if you're looking for it.
Asakusa: less buildings, lot of temples and statues. In the evening there are a lot of small food vendors. You get a feeling of what old Japan looked like. Still recommend to visit Kyoto though.
Shinjuku: not a lot to do in reality: you have the offices/business zone with one of the tallest towers (I think it's the city council) from where you have a gorgeous view on all tokyo. There is also the red light district but be warned it's not foreigners (Gaijin) friendly i.e. you can't even enter most bars or karaokes...
Shibuya: there is a big crossing you've certainly already seen on TV and lot of shops
Harajuku: lot of fashion shops and during the week-end there are some cosplay meetings
Tokyo central district: there is the tokyo tower and the Emperor's palace, otherwise lot's of office buildings.
Roppongi: it's basically where all foreigners go to party and there are some shaddy areas to avoid e.g. in some bars you have girls that come sit with you and then the owners try to extort you money by making you pay what the girl drank (think very expensive champagne). It's also where you"ll find prostitution places aimed at gaijins.

I can't recommend enough to try all the different kind of food e.g ramen, curries, sushis... You can find meat but be warned it's quite expensive. There are 2 sushis places near the fish market which are exquisite !
You'll also find a lot of convenience stores (Lawsons) open 24/7 with lot of drinks, snacks and candies with typical flavours like green tea :)

Hope you have fun.

Weeaboo?

Oh hey! My nephew will be going to Tokyo this year. I must follow this thread to learn valuable info. Be truthful ppl to all who know about the wonderful country of Japan and the city of Tokyo. Btw, just arrived at this thread by the ? about Japan. Not entering, but thank you for the giveaways for everyone else.

Aquire Japan exclusive games?

You could visit Sanrio PuroLand or the Ghibli Museum.

The giant cat bus stuffed toy and the overall tone of the museum is just so immersive and they even put some light on the more forgotten characters and sights of the Ghibli movies.
The same goes for Puroland, even though Hello Kitty and associates might not be your cup of tea, the overall tone and the really, really cute character meals are worth it.

As others have already suggested try the food. Not just the normal things at restaurants, but also the things they sell at convenience stores or visit the underground malls. They are just as big as our, but totally underground. Sometimes four to five stories low. Try the sweets. Not only the japanified Western stuff (KitKat noodle soup taste), but the traditional ones, too.

Visit the Hachiko statue. There's also a big intersection, which feels like a wall of death at a concert, if you pass it at rush hour. Eat some ekiben. There's a really famous one, but for the sake of ...., I can't remember the station name. You should also get some American fast food, as they have certain 'variants' there you won't see anywhere else. A recurring theme are the black buns. Either McD or Burger King has them, they taste just as normal as one would think, but they look like something was dropped behind the fridge and forgotten for the next twenty-something days.

And one little pointer: If you are underage(drinking age is 20 in Japan) or want to avoid alcoholic beverages, be really careful what you buy at stores. They won't check for ID on foreigners for most of the time, but their goods have barely any alcohol warning labels. So one might think they buy juice, but it's an odd tasting alcopop.

Food, food, food!
Also gaming stuff.

One day I dream of traveling the world on a culinary level. Food is an amazing thing when you think about it. It's like, you can see, hear and smell, but you can never get closer to a culture than by ingesting a bit of it.

But Japan is a place of electronics and video games too, right? So don't forget to make the best of it by exploring the technology side of the country. And have fun! :D

https://www.youtube.com/watch?v=-3lnwi1R-M4
sorry. After the end. 　( < . . . . . :D

So ...
If you have transportation expenses, Kyoto.
It is a different world from other Japan.

"Gachapon (capsule toy)" located at the airport and sightseeing spot for souvenirs is recommended. There is regionality.

If there is an artist who is interested, it might be better to head to related facilities ....
Near Tokyo? I also have something like this ...
Doraemon. Taro Okamoto. There are various things, right?

Nezu Museum
http://www.nezu-muse.or.jp/en/index.html
The National Museum of Western Art
http://www.nmwa.go.jp/en/

Fujiko·F·Fujio Museum, in Kawasaki-city
http://fujiko-museum.com/english/
Taro Okamoto Museum of ART
http://www.taromuseum.jp/english/index_english.html

have a good time not having ever been there I would be trying all the food I could find

Haven't been there yet, so I'm just wishing you a good trip!

BUMP!

As odd as it might sound,try a mcdonalds there,i've heard it's much better since they use insanely quality ingredients.

I'd love to go someday -- have a great time!

never visit japan myself, but maybe u can learn something from this game, or watch a special program by NHK called Train Cruise

bump

lots of good suggestion out there i would like to suggest a few more.

surprised no one suggested odaiba. the huge gundam is there and the place is pretty known for its japans modern science and technology museums although you can do pretty much do anything there, karaoke, shopping, food, arcade etc.

i'll also suggest ginza if you want to go shopping.

if you like live bands ikebukuro, shibuya and shinjuku has awesome live stages. My recommendations are O-east in shibuya and Live Inn Rosa(who love electro pop, edm and anime song) in ikebukuro. Shibuya and roppongi has some of the famous clubs, i recommend club ageha in shibuya for clubs

if you want to explore more and go to more risky and risque places go to kabuki- cho in roppongi, just dont get drunk too much if you're alone, that place is notorious for exploiting careless tourists. but otherwise its safe

i could suggest more if you have a specific target places or places that fit your interests.

never been there before. so have fun and a bump

You can try those famous "massage" sites in Shinjuku.

If it's only Tokyo, try to lost in Tokyo stasion XD. Just kidding.
Akiba, Ginza, Harajaku, Asakusa, Tokyo Tower, Tokyo Skytree, Forbidden city (Emperor Castle outskirt) Shibuya, Shinjuku, any many more.

Go! Go! Nippon! is already packed with information about tourist destination.

View attached image.

body pillow

watch the mighty fujiyama -san from kawaguchiko. just 2hrs train ride from tokyo

see real life size Gundam in Odaiba (rl means building size, they will remove it soon, various speculations for reason, best one is, they want to makie it moving :P).
earn money by eating
and if you are into museums check out Grutto Pass with tickets - if you plan to see more than few, it is pretty good deal.
checkout tokocheapo/tokyoweekender/timeout-tokyo for list of running festivals and events, all in english

and btw. change Japan>Tokyo

View attached image.

Bump

A lot of good advice on here already, so I'll echo a few things and try to give some other ideas. As has been previously mentioned though, a lot depends on what you're interested in.

Roppongi - mixture of seedy clubs, and high class bars. A lot of foreigners go here, as well as GIs when they visit Tokyo. Not keen myself, but there are some good places.

Akihabara - interesting to look around even if you aren't into Otaku culture and anime. There's a Maid Cafe there that's fairly foreigner friendly. It's within a shop, a chain in Japan, that has a lot of weird and wonderful things. It's called Don Quiote (ドン・キホーテ). You can find it in other areas of Tokyo easily without going to Akihabara, just look for big yellow stores with a penguin looking character on them. If you do like Otaku culture, it might be worth going to Nakano and the Sun Mall there which has Broadway on the 4h? floor. It's a condensed version of Akihabara.

Odaiba - as has been mentioned, there's a big Gundam statue that will be removed soon. A couple of decent malls too if you visit. The one next to the statue is okay, and another big one not far away called Venus Fort.

Shinjuku Contains the Red Light district, but it isn't anywhere as seedy looking as most countries. You might get a few people asking you to go into girl bars, but they won't pester you if you just say that you're not interested. High chance of getting scammed if you do go. There are some cheap and interesting places to eat and drink around Shinjuku, close to the station or at the edge of the Red Light District.
-Golden Gai (新宿ゴールデン街) is an area of very small bars, fun to go at the weekend for a bit of a different night out.
-There's also a small street called Memory alley (Omoide Yokochō) or less politely referred to as Piss Alley, full of very small old bars and restaurants. You can get some strange foods here, or just look around.
-Lastly, a cheap drinking recommendation is Medaka (めだか) in Shinjuku. It's part of a chain across Tokyo, but they're not very well known. No special food or drink in here, but some of the cheapest you'll find and it's a very open room with lots of people drinking so easy to get chatting to strangers which is quite rare in the Izakaya style bars.

Other areas like Asakusa are worth a visit, but are covered pretty well in Guidebooks. I'd recommend Kichijoji too. The Ghibli museum is close if you go. The area has a nice park and is just a nice little area to wander around in.

Day Trips
If you want to get out of Tokyo for a day, you could try
-Kamakura and the neighboring town of Enoshima - lots of temples, a seaside town, and a huge Buddha statue. You can get a day ticket from the Odakyu ticket office in the West side of Shinjuku station at ground level.
-Hakone - cable car, bit of a tacky boat on a nice lake, hot springs, and a decent view of Mount Fuji on a good day. Information on both day tickets here.
-The theme park Fuji Q Highland. You can get a package including an entry ticket and a return bus ride there, leaving from Shinjuku bus station very close to the station.
-Yokohama - less hectic city, good to wander around. The 'red brick' area of shops is quite nice, and they sometimes have festivals or events there.

Travel
If you go any further out of Tokyo, then get the JR Japan Pass. It pays for itself with one Shinkansen trip to somewhere like Osaka, Kyoto, or Hiroshima. If you don't use a Shinkansen, then it's not worth it. Just get a Suica card at the train station at the airport and charge it. You can keep topping it up a little during your holiday. It works for all trains, buses, and you can even use it to pay in convenience stores or vending machines.
As a tourist, you can get a cheaper ticket for the train from the airport into Tokyo too. If you arrive at Narita and plan to use the train to get to your hotel, then check the link here.

Whoops...that turned into a very long post. Anyway, I'm in Tokyo, so feel free to add me if you have any questions or need help finding information.

----Edit----
Two more small things...
Just remembered that there's a Sumo tournament on in January. Cool thing to see if you can. Advanced tickets are sold out, but if you go early, you can pick them up on the day.
Also, I'd recommend this book
. It's a good way to communicate even if you speak no Japanese at all. Probably too late for you to order it before you go, but you can pick it up from big bookstores in Tokyo, like Kinokunia.

---Edit 2----
Another, only in Japan, kind of place is a restaurant called Kagaya. Run by one guy and his mother maybe, bit difficult to find buy worth it. He speaks enough English to mean you can book by phone and it's worth doing so if you decide to go as the are only about 5 seats in the whole place. Basically he dresses up and pretends to be different people while serving you. You can find videos online, and I understand that you'll want to check it out if you're considering going, but don't watch too much or it will spoil the surprise. I checked it out, decided to go but didn't tell my friends what it was like :-)
It's in shinbashi, hopefully this Google maps pin works Kagaya
https://goo.gl/maps/CX8cS8Lf3tQ2

Couple more restaurant suggestions
-Iseya has a few yokitori restaurants in kichijoji. Pretty famous.
-Barbacoa, while not Japanese food, is a pretty amazing Brazilian churrasco restaurant. Not cheap, they do have different prices for different tones though. Cheapest at lunchtime on a weekday and most expensive in the evening at weekends. There are a few branches around the city, Aoyama is best rated and the only one I've been to but I imagine they're all pretty similar. It has an 'all you can eat' and optional 'all you can drink' system. This can be found in a lot of Izakaya in Japan (食べ放題 (tabehoudai) and 飲み放題 (nomihoudai)).
-This website is good for finding restaurants http://bento.com/m/e/n0.html

Trains
The websites hyperdia and Jordan are train websites that lack you check routes and times. They both have English pages. I think there's also an app called Japan trains. The stations can be a bit confusing, especially shinjuku, so checking lines, times and even platform numbers helps.