I thought it might be worth a brief post about life here in the Dormitory Maruyama, both to help with the decision of whether it's for you, and to let you know some things which might be worth knowing if you do come here. Some of these things may or may not apply to other dormitories: they each have their own facilities and rules, so I can only state with certainty what to expect at the Dormitory Maruyama, even though some of these things will certainly apply at other dorms.
Just to clear something up before I go any further, which was something I know friends of mine were confused by when I first told them I would be staying at a dormitory. A “dormitory” (寮 in Japanese) is roughly what I would know as a “hall of residence”. It is not a “dormitory” in the English sense of communal sleeping quarters. We each have our own room (there are single and double rooms at this dormitory). It is single sex, and there is an 11pm curfew at mine.
There is a dining room (食堂) where breakfast and an evening meal are served Monday through Saturday, but not on Sundays or holidays. There are also basic kitchen facilities (gas hobs, microwave, toasters) and equipment in the dining hall, which students can use to prepare their own meals, on Sundays and holidays, or lunchtimes. By “basic equipment”, I mean a few pots and pans and cooking utensils. But be aware that there are no plates, chopsticks, knives, forks, spoons, etc. for students' use: you have to get your own. Still, if you go to a 100 yen shop, you can get all these pretty cheaply (105 yen each item, in fact: the extra 5 yen is sales tax!). Not a big deal, but the information I received didn't mention this (under “what to bring” it only listed “a pair of slippers or sandals, towels, soap, laundry soap, toilet paper etc.” and didn't mention cutlery or crockery – and in fact the dorm has slippers and does supply toilet paper in the toilets).
I previously mentioned the international telephone and internet access in the room, the latter which you have to apply for. You can also have a television in your room, (which gets a few basic channels: no BS2 or Space Shower TV here!). There is also extra charge for bedding. All of this information, and costs and the like, is included in what I was sent by the school. I won't repeat everything here which is easily ascertained from the school or from the dormitory website itself. You can choose between dormitories with and without private bathrooms. As a fan of the Japanese bath, I didn't feel the need for my own, inferior, bath, so I was happy to go for one without. The shared bath here at the Dormitory Maruyama is very nice indeed. For those less keen on the Japanese shared bath experience, there are showers, which you can use at any time. But really, the bath here is very nice!
As I have certain eating peculiarities (i.e. I don't eat meat) I always expected meals occasionally to be slightly difficult for me, but as I didn't want to make a fuss, I didn't mention my preferences in advance to the dorm (although I did to the school, when they arranged homestay for me). But the fact that I don't eat meat did come up when I asked for a particular dish without the meat, and since then they have in fact been quite accommodating, giving me fish or eggs and the like instead of the meat dishes. I imagine an actual vegetarian would have more difficulty (as indeed they would eating in Japan in general), but if you don't eat meat but do eat fish, certainly I'd advise you to let them know in advance, and they'll prepare special meals for you when necessary.
Apart from the dining hall, there isn't really a communal area, so most socialising tends to be done over the breakfast and evening meals. As there are several of us here from the JLI, we tend to eat together. But most dormitory residents are Japanese. Many are students at vocational colleges (専門学校), but there are even a few high school students here. We've become friendly with a couple of the Japanese vocational students.
I think that covers most things which you won't find in the information from the JLI or on the dorm website. As ever, if anyone who has stayed at this, or any other, dorm, wants to add anything, they can make comments.