The girl was running faster than she ever had before - so fast that her feet pounded against the soft ground, the impact sending shockwaves of pain all the way from her knees to her chest. Her Shinigami robes (and indeed, most of her face) were caked in a mixture of dirt, blood and sweat, the palms of her hands were blistered and bleeding. Outstretched in her right hand was her Zanpakuto - a slimline wakizashi that answered to 'Umiko'. The blade was spotted in blood.
A stray twig scratched against her face and blood began to flow.
She stumbled, though used the momentum to travel faster. Finally, gasping for air, she arrived at the forest clearing. Her chest heaved and she was sure she had leaves in her hair but pushed all thoughts aside at the sight of the monster in front of her.
She had been chasing the thing for many weeks, investigating a series of mysterious deaths that racked the poorest districts of Rukongai. It was not unusual for Hollows to gather in such areas, despite what was usually a very low level of reiatsu. On the contrary, most Hollows scavenged on these areas, preying on the absolute lowest of the low. What was unusual, however, was the eyewitness accounts that followed these attacks. If they were to be believed, and until recently the girl had been neutral on that front, then these eyewitnesses had all heard music shortly before the Hollows appeared to ravage their victims and after they finished. Even more strangely, the Hollows focussed on one kill and one kill only. No matter how many people threw rocks at them, lit their bodies on fire, the Hollows did not respond, waiting until the music sounded again to return to reality and leave.
Naturally, everyone on the thirteen squads was perplexed, even moreso when preliminary investigations revealed that not only were the attacks carried out in districts that could not possibly communicate with one another, eliminating the possibility that it was all some sort of prank, but they seemed to follow a pattern. Each attack had happened at sundown on the 3rd of the month.
The girl had been sent out to observe Hollow behaviour in the last of the poorest districts to remain. Hayaido - a place that stank so strongly of blood and piss that she had had to bite her lip to avoid wretching.
She strengthened her grip on Umiko and winced at the sting from her broken hands.
"Did you think I wouldn't catch you?" she panted. "How dare you be so presumptuous!"
The Hollow took in the sheen of her sweaty face, the bloody wound on her cheek and said nothing. Had she not known any better, the girl might have assumed that from its behaviour it simply had not noticed her, except she knew that was not the case. She had cut off two of its legs, after all, and she could feel its eyes boring into her the whole time. It was almost as if it had no interest in her, which was even harder to believe than the strange accounts that had caused her to investigate in the first place.
Then, there it was, exactly as the witnesses had claimed. A strange kind of music drifted through the trees, music quite unlike anything the girl had heard before. It did not sound like any kind of instrument she had ever come across and made all of the hairs on the back of her neck stand on end. It was a sad sort of tune, though high pitched and lovely and the girl was unable to tear her attentions away from it.
What the hell is happening? she thought, trying to think clearly and plan her next move, but ultimately failing miserably. The music muffled her every thought; it was like trying to make out a whisper in a crowded room.
The music stopped as quickly as it had started and the girl squeezed her eyes shut, attempting to clear her mind. She glanced across at the Hollow and saw that it was shaking its head in an effort to do the same. She jumped, Umiko extended in front of her while the Hollow remained still and embedded it deep in its mask.
Her mission had only ever been to investigate, not to get directly involved, though as the Hollow's body disintegrated into thin air before her eyes her thoughts went back to the music. Things had just gotten a whole lot more complicated than a few Hollow attacks and strange witness accounts. Chewing the inside of her mouth and sheathing her zanpakuto, the girl wondered with a certain amount of dread how on earth she was ever going to explain any of it to her captain.