One day, Yan, who was receiving the commission as usual, was poisoned by a poison called Qisha, which was exactly the same as the poison poisoned by He Jiu's master, Immortal Cizhen. However, the poison was cured soon, which made He Jiu confused. Gu Ziyun also said something after treating Yan, which revealed the truth of that year...
Concept: The author is suffering from secondary disease