Prologue:
During the Japanese Civil War, there was a man named Hitokiri Battousai, who was feared by many. At the end of the war, he disappeared without a trace… and so did the unknown shadow that always followed him.

Chapter 1:

A dark figure, resembling the Hitokiri Battousai sits in a tree, watching a battle intently.
"They're at it again," she sighs. "Aren't those two ever NOT at one another's throats?" she wonders aloud. Shinomori Aoshi and Himura Kenshin, whom she calls "Shinta." She knows that the fight always ends in a draw. 'Aoshi's weaknesses are so obvious. He's completely open when attacking, kodachi or not. All you have to do is grab it and he's totally disarmed. Why can't Shinta see that?' she wonders to herself. 'Of course, with only a sakabatou, he can't parry and attack at the same time. Idiot. I'm the one who deserves the title "Hitokiri Battousai," not him,' she finishes her thought, continuing to watch. 'Ugh!! They're sooo awful! Don't they have any uniqueness to their fighting style! This is kenjetsu, but still… couldn't they be just a bit more creative?? What a bore!' Such thoughts of two of the best swordsmen of the age show her skill level in themselves. "Well… gotta give Aoshi-kun credit… he's pretty original… but Shinta! Oh you shame the Hiten Mitsurugi Ryu!" she whines, covering her eyes. She too, knows the Hiten Mitsurugi Ryu sword, and knows it better than the infamous Himura Battousai.
Feeling a well-memorized ki present, she glances to the place she feels it from. Saitou Hajime, as usual, is hiding and seeing exactly how strong Kenshin still is, but the onlooker in the tree knows he's not, and cannot be ever again unless he becomes the hitokiri once more.
'He's not what Saitou's looking for. If Shinta refuses to kill, he's of no use to Saitoh, no matter how strong.'
As usual, Kenshin is drawn away by another emergency, and the battle ends in a promise from both sides to finish later, and for now, a draw. Kenshin hurries away, and the figure jumps from the tree, landing behind Aoshi, pushing the handle of her sword against his back. Although Saitou is still watching, she doesn't care. 'What difference does it make? I'll reveal myself soon anyway. Besides, he could be of some use,' she thinks to herself.
"Who are you?" Aoshi asks her calmly.
"Unless you want to die, I'm not going to bother telling you," she answers, in an equally calm tone.
"What do you want then?"
"I will warn you this much, the Battousai is mine, stay away from him. If anyone kills him, it will be me. And a further warning, Aoshi-kun," she grins slyly, using a familiar tone. "I'm much stronger than either you or Battousai could imagine. I will not tolerate interference from you or you, Saitou Hajime," Aoshi remains emotionless, but Saitoh, surprised, abandons his hiding place. She pulls a letter from with her robe, and hands it to Saitou. "Give this to Battousai and if you read it, I'll kill you."
"I'm not a messenger boy!" Saitou protests.
"And I wasn't asking," she replies, turning, relaxing her grip on the sword for a moment. "That is for Battousai's eyes alone, and if you draw those swords, my patience will end, and I don't feel like killing anyone tonight," she grips her sword, calming herself, merely by holding it. Saitou curses under his breath, but the mysterious female swordsman knows it will be delivered, and walks away confident.
'Strange,' Saitou thinks to himself, looking at the address on the paper.
"What's so fascinating about the address?" Aoshi asks.
"It's addressed to Himura Shinta… who's that?"
Aoshi merely shrugs and walks away.