A/N: Okay, since I think I've been confusing people, I've decided to clarify a few things (thank you, Bloophearts for pointing that out!).
1) Chihiro has no memories of the Spirit World, 2) Chihiro figured out all the incidents were connected to reflective surfaces (water, windows, mirrors, etc.) so that's why she put the mirror in front of her bed – to confront the source of her problems rather than avoid them like she had before.
Sorry for confusing everyone!
The first time it happened, Chihiro had fallen out of her seat in class. Wide eyed and shivering profusely, she was having a hard time forming words since her tongue was stumbling all over itself, so she settled for pointing a shaky finger at the window instead. When a dozen pairs of eyes turned to look though, all they saw was foliage. She avoided looking out the window after that.
The second time it happened, Chihiro almost dropped a cup. Though she managed to catch it in time, the jostling had caused most of her iced water to pour out all over her pants. She'd left the restaurant with a misleading water stain on her pants and her mother's atrocious hot pink sweater wrapped around her waist. She stopped looking into her cups after that.
The third time it happened, Chihiro was just about ready to tear her hair out. "What are you?!" she screamed at the water as she scrambled out of the pool. Unfortunately, a little five-year-old boy who was wading in the waters directly in front of her thought she was yelling at him and promptly burst into tears. That week, she'd gotten a lot of weird looks and even more glares every time she left the house. She resolved never to go swimming after that.
The thirty second time it happened (or maybe it was thirty first? Chihiro wasn't sure. She stopped counting some time after twenty.), Chihiro finally relented and placed a full length mirror, which she'd thrown a sheet over after the seventh (eighth?) time it happened, in front of her bed.
She'd bought the mirror from a withering old lady a few years back. The woman claimed that the mirror was a portal to another world, that the jewels in the rings she sold were solidified dragon's blood, and that the toothed necklaces were not made from shark teeth but from a snake spirit's fangs. Chihiro hadn't believed a word she said, but she needed a mirror and the lady was selling it cheap, so she bought it. Now though, she was kind of regretting her purchase.
For a moment, Chihiro stared at the mirror, contemplating if confronting her problem was the best course of action, and decided that yes, yes it was. So, without further ado, she ripped the sheet off with a sharp tug and took a deep breath.
She was going to go about this like a calm, rational human being.
"What are you?!"
So much for calm and rational.
The figure in the mirror which stared back at her was not her own. It was a teenage boy a few years older than her with shoulder length green hair and eyes that seemed to hold unspeakable sadness.
He looked...familiar.
Chihiro racked her brain for knowledge as to who he was but she couldn't remember for the life of her who the boy was. That didn't stop her from ranting at him though because potential acquaintance or not, he was practically ruining her life what with him popping up all over the place.
"I've been seeing you everywhere I go, and people are starting to think I'm insane!" She'd started pacing back and forth with her hands flying all over the place, gesturing wildly to convey her anger and irritation.
When the figure still said nothing, she whirled on the boy and tried directing all of her anger on the single spot between his eyes, hoping she'd suddenly gained the powers to spontaneously combust someone with her glare. "Well?" she said, her voice frosty. "What do you have to say for yourself?"
Silence.
Chihiro let out a frustrated growl and flopped face down onto her bed. The inside of her mind was like a tornado whirling with thoughts and possibilities as to what this boy was. He wasn't human, or at least, she didn't think so. She lifted her head off the sheets enough to glance at him from the corner of her eye.
He was still there.
Chihiro rolled around so her back was to the boy and continued to think. Eventually, after minutes of contemplating, her mind supplied her with the most logical answer it could think of as to what the boy was: a ghost.
She, Chihiro Ogino, was being haunted by a ghost.