Language
Unless you've got roughly a year or more (and a lot of free time) to prepare, there's really no way to go from zero to generally functional in Japanese before a trip. I had roughly three months to cram as much into my brain as I could. By the trip, I could recognize ~300 kanji and ~1,500 words, and could construct mildly interesting sentences (e.g., これを書いている人は日本語が下手です。"The person writing this is bad at Japanese."), but this wasn't nearly enough to be independently functional. 300 kanji may sound like a decent number, but it's roughly only 14% of the total kanji that literate Japanese adults are expected to know. So that's not a great hit rate. There is some good news, however: the preparation did help in a few areas (recognizing some food items on menus, being able to operate a Loppi machine to get NJPW tickets printed).
If you are making a trip (even on short notice) and do nothing else with the Japanese language, learn the katakana syllabary. There are only 46 symbols (minus diacritic marks) and plenty of opportunities to practice reading actual words. It's estimated that about 10% of modern Japanese consists of loanwords, the vast majority of which come from English (or are loanwords from other languages brought into English first). All of these loanwords are written in katakana. While there are some caveats with respect to divergence from original meaning, this generally doesn't happen with concrete objects like food and drink. Especially if you need your daily dose of caffeine like I do, it's useful to know that you can get a カプチーノ (cappuccino) with your breakfast at Denny's without waiting for an English menu (if they have one). Even if there's a native Japanese term for something, you'll often see the loanword instead in katakana because it's "cool" to use English terms.
If you have a little more time, it's useful to learn the hiragana and then basic food kanji and terms, like 肉 (にく, niku = meat), 豆 (bean, often in terms related to soybeans), 牛 (cow, such that 牛肉, gyuuniku = beef), 魚 (さかな, sakana = fish).
Don't rely on Google Translate to help much. It might work with straightforward words and phrases, but Japanese is a highly context-dependent language with grammatical structures very different from those of English, so it's probably a coin flip as to whether you'll end up more confused than you were before if you're trying to work with complete sentences.
Don't rely on Google Translate to help much. It might work with straightforward words and phrases, but Japanese is a highly context-dependent language with grammatical structures very different from those of English, so it's probably a coin flip as to whether you'll end up more confused than you were before if you're trying to work with complete sentences.
Food
Speaking of food, I was surprised how inexpensive it was to eat in most places in Tokyo. You can eat out and eat well for less than 3,000 yen per day, and significantly less than that if you're willing to fill up on onigiri (rice "balls", really more like pyramids, wrapped in seaweed), which are usually around 110 yen each.
If sushi is your thing, conveyor belt sushi (回転寿司) restaurants are an efficient way of getting your fill. You'll break the 3,000￥/day budget here but not terribly so, especially if you like the cheaper plates of sushi. You can have a good sushi meal for 2,000-2,500 yen, which is far less than you'd pay for the equivalent amount of sushi in most places in the United States.
One of the few exceptions to "inexpensive food" would be pufferfish (fugu). I ate this at Genpinfugu, a short walk from the Ueno station in Tokyo. Beware that, if you go, everyone in your party should be willing to try pufferfish, because the restaurant specializes in it to the exclusion of nearly everything else. I have to imagine that, due to the trouble of retaining a licensed pufferfish chef, that would be the case elsewhere too.
Many restaurants do not accept credit cards, so carry enough cash on you. Also, some ATMs do not accept foreign debit cards, so don't wait until the last minute to try to find a place to get cash.
