- World background: The world of cultivation is divided into three major forces: "Tianyan Sect", "Netherworld Palace" and "Ten Thousand Demons Valley". After a thousand years of war, the "Demon Sealing Contract" was signed, but undercurrents are surging.
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- Protagonist (sufferer): Su Han
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- Before time travel: A descendant of a modern Chinese medicine family, proficient in acupuncture and toxicology, fell down from a building to save someone and time travel.
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- After rebirth: An outer disciple of the Tianyan Sect, the original master had his spiritual root disabled due to the "Three Yin Jue Meridians" and was bullied to death by his fellow disciples. After Su Han was reborn, he awakened the "Reverse Scale" physique (absorbing negative emotions to strengthen himself, and initially suppressed inner demons), and was bound to the "Ghost Doctor System" (which can analyze the pharmacology of the cultivation world and unlock ancient poison techniques).
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- Protagonist (attack): Xie Wuwang
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- Identity: The young master of the Netherworld Palace. He looks sinister and ruthless, but in fact he is possessed by the "Love Gu" (you need to practice double cultivation with the person you love most on the first day of every month to renew your life), which has a mysterious resonance with Su Han's scale-reverse physique.
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- Bond: He was Su Han's sword slave in his previous life. He turned against him due to a misunderstanding. After his rebirth, he secretly guarded him in the name of torture.
Purpose: A small test of one's skills