Ten thousand years ago, the immortal-demon war came to an end. The demon lord Ji Yuan, burdened with curse poison, guarded the Cangyuan alone for ten thousand years. Modern girl Shen Zhiyao accidentally crossed into the demon realm. Living day and night together, the two gradually developed feelings for each other. However, this encounter relied on a spacetime rift from the very beginning. Coming from another spacetime, she was ultimately destined to return home. Old immortal-demon grudges and the shackles of destiny lay across them, and a brief, warm romance had long since been written with a parting ending.