There's only one chapter left, and I'm afraid we won't get an answer to any of the most important questions...
...like, why were her friends' ghosts/spirits/whatever so desperate to kill Miki as soon as possible? Aren't they supposed to be, you know... her friends? Her brother is dead as well and yet his ghost apparently did everything he could to keep her alive, so why were her 'friends' such dicks instead? I know Miki admits she may have subconsciously wanted to go with them because she felt alone, but... they weren't just a product of her mind, no? They all seemed to have a life of their own... plus, her brother's ghost just randomly appeared behind a tombstone, and that can't just be Miki's mind playing tricks on her, can it? Even the psychic said his spirit is actually there...
Also, what's with Miki's fear of darkness? Considering what happened that put her in a coma, wouldn't it make more sense for her to be afraid of water? And what's with the blimp? Why did everyone seem to see monsters while Miki was the only one who couldn't? What did Mutsuki, Ryouhei and Tatsuya disappearing for days have to do with anything? Where did they go, and why?
I really, really hope the final chapter won't be just eight pages long like the other ones... though I'm sure not even one of these questions is going to be answered.