Ghouls Just Haunt to Have Fun

The spirits in the story felt so lively and mischievous—sometimes more so than the human cast. Did the author intentionally give the ghosts such vibrant personalities?

The combination was fresh and fun, but I wonder whether the author started with the mystery or the supernatural elements first. Which came first during the creative process?

The setting felt like a character itself, full of personality and secrets. Did the author base it on any real place or craft it entirely from imagination?