Well, first off I'll tell you that you're not the first to post about this and won't be the last. Hell, I think I even posted asking about Japanese universities at one stage.
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Before reading what I've typed below, I'd say that you should sit yourself down and try to answer most or all of nice_gaijin's questions. If you can't, then take some time to think it over - this won't be a four year+ holiday; it'll be university in a foreign country which you may have never even visited. [/Edit]
I'll try to relay some of the information I've come across on these forums before, but I can't guarantee its accuracy - you'll need to search JREF using the 'Search' function and find the specific threads for details. Even then there's no guarantee, so it's best to contact specific universities when you have some idea of what you want to do. Each one is likely to have slightly different requirements, so it's best to ask them directly to find out*exactly* what is expected of you.
- Unless you attend Sophia (
http://www.sophia.ac.jp/e/e_toppage.nsf) or an international university that teaches courses using English, then you're going to need to become proficient in Japanese to the level that you can study at a Japanese university. Even at Sophia you'll need some level of Japanese proficiency to survive in Japan for a full four years or more. I'm not really up-to-date on what Sophia's offering in terms of English-language based classes, so again it'd be wise to consult their website, previous posts on JREF, and the department over at Sophia that deals with all this.
- For most universities you'll need to sit some tough examinations in various fields - which generally don't seem to be based specifically around the subject you're hoping to study at said university. One of these examinations will no doubt be a Japanese proficiency test. They might also require that you sit the JLPT (Japanese Language Proficiency Test) to prove your competence in the Japanese language.
- Keep in mind that if you're going to be studying something in the Electronics/Telecommunications/Computers field, then you'll also need to be able to cope with all of the technological terminology used - in Japanese.
- I don't know which universities are well-known for their technological departments (or whatever field/department might deal with what you're interested in studying) but Tokyo university (Toukyou daigaku) is generally considered the number one state university and very difficult to get into.
Kyoto university (Kyouto daigaku) seems to be considered as being on a similar level, although perhaps slightly below Tokyo university. And then there are private universities, such as Waseda, Ritsumeikan (sp?), Sophia, etc. etc.
Hope this helps to get you started. I strongly recommend searching the forums for information from the folks who've been there and done that, and then contacting the universities of your choice for the information that's specific to each university.
Enjoy! (And this is all assuming that you're sure you want to attend university in Japan, which - depending upon who you are and where you go - could be one hell of a nightmare if you're lacking in language ability, or even if you're not.)