It's hard to say for sure. Manhwa often have twist and turns. The boy next door could be a vampire if the story takes a supernatural turn and reveals it later on.
Rachel could be a great character to pair with the boy next door. She's ambitious and talented, and their relationship could be full of musical duels and passionate arguments about art. They could both push each other to be better singers and performers.
Overall, 'Do It Next Door' manhwa could be about various themes like love, friendship, or mystery within a neighborhood setting. Maybe there are secrets being uncovered or heartwarming moments shared among the characters.
I'm not sure specifically as I haven't read it in detail. But generally, it might be a story about the relationship between Lola and the boy next door, perhaps a coming - of - age story with elements of friendship, first love, and self - discovery.
It's not impossible. Manga creators often come up with unique and surprising twists, so the boy next door could totally be a vampire. It could add an exciting element to the story.
Well, if we consider a more general 'the boy next door' story. Maybe the boy next door is a bit of a mystery at first. He keeps to himself and no one really knows much about him. But then one day, the main character's pet gets lost and the boy next door turns out to be really helpful in finding it. This leads to them becoming friends and they discover they have a lot in common, like a love for the same kind of music or books.