I’m currently living in Japan, having both traveled through and studied abroad here before.
First, decide where in Japan you want to visit. Do you want to do a tour of many cities? If so, I would cover some of the famous basics like Tokyo, Kyoto, Osaka, Nara, and Hiroshima/Miyajima. They’re all within a few hours of each other by train, but if you must pick one place (since trains can be expensive, if you don’t want to be on them forever) I’d recommend the Kansai area (Kyoto/Osaka/Nara) because you can really get a good sampling of Japan (from traditional to high-tech and trendy) in just the one place.
Shopping will be excellent in any larger city. Tokyo, being the biggest, is certainly the best, but Osaka and Kyoto are quite nice too. There will be famous and historical sites in all of these places, too; and while worth visiting on their own, there are also usually lots of traditional shops around them, perfect for buying unique accessories or souvenirs for people back home.
As for accommodation, there are the usual hotels, hostels, and also traditional inns called ryokan and bed-and-breakfast type places called minshuku. I’d really recommend doing a ryokan or minshuku at least one night you are in Japan, because you usually can sleep on a futon, wear a yukata (cotton summer robe, like a kimono but simpler) supplied by the inn, try a Japanese bath (depending on where you go, might be fueled by a hot spring!— and often outdoor in a pretty garden or something), and have a traditional Japanese dinner and/or breakfast.
Good luck! (And congrats on how far you’ve come!). I hope you get to come over here, it’s a pretty cool place. And if you have any more specific questions (like once you know which city/cities you want to visit and want to know about specific spots in the area), feel free to ask them here or send me a message. I am particularly familiar with the Kyoto area (I lived there for four months), but I have visited all the other places I mentioned, most of them several times.posted almost 5 years ago