Yes, unfortunately, Kurama passed away in the manga. This occurrence brought about a lot of changes and emotions for both the characters and the readers.
The reason for Haitang's death was because she had discovered the secret of Liu Sheng Piao Xu. Piao Xu had not abolished her martial arts and had been hiding beside Duan Tianya. She looked like an ordinary woman, but in fact, she was a minister who had been secretly getting rid of the Divine Marquis and preventing him from usurping the throne. In order to keep the secret, Yagyu Piaoxu killed Haitang. In addition, Haitang also discovered Piao Xu's true identity. Piao Xu did not want Duan Tianya to know that she was an assassin, so she chose to kill Haitang. However, these search results did not provide specific background information or plot details, so there was no definite answer.
In the original novel of 'The World of World', Yueyue drowned after falling into a water tank. While Zhou Rong was hospitalized, Yueyue accidentally fell into the water tank while washing the dishes outside the room, causing an unfortunate accident. This plot was set in the original novel and did not change in the TV series.
Hong Siyang died from being killed by Great Grandmaster Ku He. Hong Siyang was a peak ninth-level expert and was considered a shield for the Qing Emperor's identity as a Great Grandmaster. In the battle of Dong Mountain, Hong Siyang, as the Qing Emperor's scapegoat and bait, was killed by Ku He in one move. Hong Siyang's death was an important sacrifice for the Qing Emperor. It exposed the Qing Emperor's true strength as a Great Grandmaster. Hong Siyang's identity as a eunuch meant that his martial arts could only reach the peak of ninth-grade and could not break through to the realm of Great Grandmaster. As a result, he became stronger under the Qing Emperor's guidance. The Qing Emperor deliberately made Hong Siyang his shield to lure out the other Great Grandmasters and achieve his goal.
Hong Siyang died from being killed by Great Grandmaster Ku He. In " Celebrating Years," Hong Siyang was considered a shield for the Qing Emperor's identity as a Great Grandmaster. In the battle of Dong Mountain, he was used as a scapegoat and bait for the Qing Emperor and was killed by Ku He in one move. Hong Siyang's death was an important sacrifice for the Qing Emperor. It exposed the Qing Emperor's true strength. Thus, Hong Siyang's death could be said to be a sacrifice for the Qing Emperor's interests.