I wanted to throw in a few things, but the best advice I have is this: you are probably not "well-dressed" by Japanese standards. People here dress-up to go to the grocery store. Please bear in mind that what you consider casual is probably EXTREMELY casual to the Japanese. That's not to say you can't run with it(gaijin smash!), but I have become a much snappier dresser while I have been here because not dressing well is just one more way to feel awkward in this homogeneous society. My advice: whatever clothes you bring, make sure they are the best of your best.
Down to the nitty-gritty, this will be a ladies-centric post, though I will note a few things about dudes at the bottom.
Something else to NOT bring: Jewelry. I wore a lot of jewelry in the US, but jewelry may not even be allowed in your school. On special occasions(entrance/exit ceremonies, graduation, etc), I see a lot of pearls, so I've actually been able to wear mine, but rings and earrings are almost always a big no-no. Of course, ESID, and I know some people who just play the "clueless gaijin" card and keep wearing what they like, but I really wish I had left all that at home and not taken up so much space on stuff I haven't worn since I've been here.
Clothing: As a larger lady, I will say this regarding clothing: BUY THEM AT HOME. EVERYTHING. Bras, underwear, TIGHTS/LEGGINGS/HOSIERY. If you are above a (thin) US size 12, you will be SOL when shopping here. If you are a curvy size 10, you may even have trouble. As mentioned, pants do not accommodate hips or butts, and my god, if you have a bosom, don't even bother trying on anything other than stretch shirts in this country. If you wear button-ups, bring them. You will NEVER find one that fits you here. That said, I have found a bunch of clothes that fit me--but they are all stretchy. If you want something well-tailored, you'll need to bring it. If you are a woman who wears anything larger than an 8(US), you will have a hard time finding shoes. Honestly, I brought 3 pairs of heels and I have only worn one of them once. Find reasonable, comfortable flats, sneakers, SLIP-ON shoes, though feel free to bring fun shoes you'll run around on the weekend in. If you are a tall woman(for Japan, that means over 5'6"), expect to have trouble finding clothing with the proper proportions regarding arm/torso/leg length.
Toiletries: as noted, bring deodorant and toothpaste. I have no problem whatsoever finding perfectly suitable Q-tips, so I wouldn't bother wasting space. If you are a moderate or light flow gal, the tampons here are fine. If you are heavy, bring your own. They also have a slew of panty-liners that are perfectly normal. MAKE-UP: I am a pale, pale white girl, and when I ran out of powder, I had to buy the "clear" to get it light enough for me. I kid you not. If you are anything other than olive-skinned/asian heritage, you will need to bring your own(if you are blush- rather than olive-skinned, even if you aren't that pale, you'll probably want to bring your own). The Korean "Skin Food" make-up does work for me, but it's damned expensive and sometimes hard to find other than in a big city. Sun-screen--the stuff over here usually comes with skin-bleaching in it, so I had some sent to me. Shampoo-I have thin, fluffly blonde hair, and I have found most shampoos here are too heavy and weigh my hair down with the build-up(meant to moisturize and treat the thick Japanese hair). I had to have clarifying shampoo sent from the US, and what a difference! I did find some Pantene that works well, but it took me a year and a half to find something that worked, so I suggest bringing some if you're anything like me.
Medicine: Psuedoephedrine is illegal. Phenylephrine is legal. If you live in a meth state with regulations, the stuff you have to sign for, you cannot bring. BC is possible to get, even more obscure stuff(Yaz, for example), but you may have to make appointments more often. Japanese people basically don't use BC, but it is possible to get some, and I've had no real hassles about it. Painkillers--I love Excedrin. They sell it here for like 400 yen per pill. Bring some from home. If you get heartburn, the stuff here sucks. Bring your own.
Okay, now the note for dudes: I have a very thin friend, but his shoulders are moderately broad, and it is IMPOSSIBLE to find dress shirts here. He's also 6ft tall, so the arms on everything are all too short. If you will have to wear suits/dress shirts(this is pretty normal, by the way), and you're over 5'8" / are anything other than what could be called "petite" in build, you will probably have trouble finding well-fitting dress shirts. If your feet are over US size 10, or they are wide, you will have trouble finding shoes. Guys, I know you probably only own like 4 pairs of shoes, but seriously, you're going to want to bring at least two pairs of dress shoes, two pairs of sneakers(one indoor, one outdoor), a pair of flip flops, and a pair of casual shoes, as well as at least one pair of slip-on shoes you can use for your indoor shoes at school. If you're going to live in a place that's cold, you'll probably also need a pair of boots to stomp around the snow in. Think ahead!
Finally, a note for everyone: DON'T PANIC!! If there is something you need, you can probably have it sent over, no real problem. Make sure you have the essentials and you'll fill in the rest, one way or another.
JET 2010 ALT - Hiroshima Prefecture, Shobara Jitsugyo High School