Who has read the novel in which the protagonist is trapped in a school by a ghost and plays a horror game, and the protagonist is heartless and saved by Sima Yi?

According to your description, I guess you may be asking about the mysterious cartoon "Mysterious Campus: Mysterious Game" created by cartoonist Alfred Hui.

The story background of the cartoon takes place in a school called Wensheng Academy, where students play a horror game called "paranormal game". In this game, players need to complete all kinds of strange tasks and interact with ghosts. The protagonist Lan Mengru was saved by Sima Yi because of being haunted by ghosts, and launched a series of thrilling adventures.

In the story, Lan Mengru is saved by Sima Yi, who is possessed, and gradually discovers the mysterious power hidden in himself. With the cooperation of other students, they explored all kinds of supernatural phenomena on campus and gradually uncovered a series of secrets in the school.

But I don't know if comics have been adapted into novels. You can try to search for relevant information online, or learn more about this novel through other channels.