Japanese sci-fi/fantasy movie with young-ish girl as lead

I saw this movie probably about 10 years ago, it was a Netflix disc and was in Japanese with subtitles.

The opening and ending scene was both in a a plain, almost all white/ cream) apartment with a young-sh/ young adult female. The only really items was a wall with pictures or drawing. The ending scene she walked out onto her balcony.

The movie was set in some strange, possibly CGI, world that was very dark, almost black and white. I also remember some weird scribble monster thing on an all white background. The main characters (two of them) had to sneak around the world accomplishing something. There were just strange creatures everywhere.

Unfortunately, I watched this movie when I was young and very sick so it was hard to remember, but it stuck with me all these years and I really need to find it again.

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