Please recommend a fantasy novel. I don't remember its name.

In one of the plots, the boy created a killer organization. In order to take revenge on his arrogant childhood sweetheart, the boy stipulated that whoever dared to marry her would be killed. It became the number one killing order. The main character's surname should be Gu.
The main character's master should be called Old Demon. He could open up his own space.

Answer 1

If you provide more information, such as the plot of the novel, the author's name, or the publishing platform, I can recommend the novel more accurately for you. For now, I can only recommend some fantasy web novels, such as " Demon River "," Reverse Universe Begins from Celestial Bane "," Fantasy: I Can Plant Talents!" Divine Arts, Heavenly Dao Mad Supremacy, Nine Star Soul Cultivation Technique, and so on. I hope I can help you.