The hidden library became Aiko's new training ground, but the focus shifted from identifying yokai to manipulating the subtle energies around her. Under Master Jin's patient tutelage, she learned the delicate art of weaving spiritual threads, creating the tracer ward Kaito needed.
It wasn't about raw power, Jin explained, but precision. He showed her how to draw ambient spiritual energy, infuse it with a specific intent – Mark. Follow. – and then attach it to an object like an invisible, psychic fingerprint. It required intense focus, a calm mind, and the heightened sensitivity Aiko now possessed.
She practiced on small stones, on leaves, even on Mochi (who seemed mildly annoyed by the faint tingling sensation). Kaito would then test her, trying to sense the ward without touching the object. At first, he could feel her clumsy attempts easily. But Aiko learned quickly. By the end of the day, she could place a ward so subtle, so perfectly attuned, that even Kaito had to concentrate intensely to detect its faint signature.
"She is ready," Master Jin declared, giving Aiko a rare, approving nod.
That night, under the cloak of the estate's deepest slumber, Kaito and Aiko moved like shadows towards the archives. Kenji had disabled the security cameras along their route, creating a blind spot for their operation. The archive room itself was cold, silent, and smelled faintly of old paper and dust. The rows upon rows of shelves seemed to stretch into infinity, holding the weight of centuries of secrets.
Kaito moved with practiced ease to the sections Kenji had prepared. He placed the forged scroll, detailing the fake Tengu pact, among the authentic alliance records. Then, he led Aiko to the financial section, sliding the small, doctored data chip into a hidden compartment within an old, iron-bound ledger.
"Now," Kaito whispered, stepping back.
Aiko approached the scroll first. She took a deep breath, calming her racing heart. She closed her eyes, gathered the ambient energy, wove her intent into it, and gently "pressed" the invisible ward onto the scroll's silk ribbon. It felt like tying a thread only her mind could see.
Next, the data chip. This was harder – the object was small, cold, and held no inherent energy of its own. She focused, picturing the intent – Mark. Follow. – and attached the second ward to the chip's metallic surface.
It was done. The bait was set and tagged.
They retreated from the archives as silently as they had come, leaving no trace of their presence. Back in the relative safety of Kaito's quarters, the true tension began.
"It could be hours," Kaito said, pouring them both a cup of calming chamomile tea. "Or days. We don't know when they will make their move."
"I'll know," Aiko replied, her hand instinctively going to her chest, where she could feel the faint, psychic "pull" of the two wards she had created. They were like tiny, sleeping beacons in her mind. "The moment someone touches them, I'll feel it."
She sat in the quiet living room, the city lights painting patterns on the floor, Mochi purring softly beside her. Kaito sat opposite her, pretending to read a book, but his gaze kept flicking towards her, his body coiled with a tense energy.
They were no longer just hunter and prey, teacher and student, or even protector and protected. They were partners in a silent, deadly waiting game, listening for the faintest click of their trap being sprung within the heart of their own home. The house of spirits had become a house of spies, and the longest night was just beginning.