I haven't come across a Chinese novel that is clearly centered around the phrase 'you have guts'. Chinese novels cover a wide range of themes, from love and family to war and adventure. While courage is a common trait in many novels, there may not be one that is so simply named or themed as 'you have guts'.
Their relationship could start as a mutual admiration for each other's music. The lofi girl might be drawn to the synthwave boy's energetic and unique synth sounds, while the synthwave boy could be attracted to the lofi girl's calming melodies. They could start collaborating on small music projects, which would lead to them spending more time together. As they get to know each other better, they might find common interests outside of music, like a love for a certain type of art or a particular coffee shop. Their relationship could then develop into a close friendship, and eventually, romantic feelings might start to bloom as they realize how much they complement each other.
One possible plot could be that the lofi girl, who is often associated with a laid - back and mellow vibe, meets the synthwave boy, who has a more energetic and retro - futuristic feel. They could start by collaborating on a music project. Maybe the lofi girl is looking for a new sound and the synthwave boy's unique style catches her attention. They face some initial differences in their musical approaches but gradually learn from each other and create a new genre of music that combines the best of both their worlds. Their relationship could also develop romantically as they spend more time together working on their music.
Guts is purely fictional. It's a concept or character that exists within the realm of imagination and creative storytelling rather than being based on reality.