This isn't really groundbreaking in Japan -- at least not in terms of content. Japan has had a genre pretty similar to this movie called "girls love"; the stories are usually centred around high school or college students who do little more than hold hands and, ultimately, make some statement about 'gender doesn't matter'. What IS unusual about this movie is the fact that it's live action -- most of the girls love genre is animated -- and that it was shown in theatres (even if it was only a few) instead of being released directly to DVD.
I don't think it was particularly groundbreaking, but neither was it usual. It certainly does seem to have opened up the floor for more live action girls love films, which I applaud, even if the genre is sometimes frustrating (too many vapid expressions; not enough action, or even hints of action). Interestingly enough, the book upon which this movie was based was not nearly so innocent (well, it was, because the characters are essentially the same and the so is the story, but there was a lot more nudity and sex).
I'm sorry to hear that the DVD extras are so few. I've been wavering between purchasing the Japanese DVD or the American one because I wanted to support the licensing of Japanese films in America, but the Japanese version claims to come with several other extras and I'll probably spend my money on that instead.