Who whispers among the spirit pillars

Five years ago, a woman named Lu Shuang vanished from a mission with the Demon Slayer Corps, never to be heard from again. Now, a young woman with crimson hair and azure eyes walks the land, claiming to be an assistant to the master, yet hiding a secret she can never let anyone discover—she is a demon. Cangyan, the Soul Pillar, a spirit who commands dragon flame, had long sensed something amiss about her, but chose to remain silent. Between them existed a precarious, unspoken understanding... until Lu Shuang finally broke that silence to ask for help: she was searching for a younger brother. Cangyan brought her to the Soul Pillar Estate, unaware of the rift that decision would tear open. His comrades within stood with swords in hand as the interrogation began.