I'm not sure specifically as I haven't read it. But generally, a 'light novel' about vampires might be about vampire characters, their lives, perhaps their relationships with humans, and their feasts which could be related to blood - drinking or other vampire - related activities.
Since it's a 'le festin de vampire light novel', 'le festin' means 'the feast' in French. So it could center around the feasts that vampires partake in. This might include the social aspects among vampires during these feasts, like power plays, hierarchies being established or challenged. It could also touch on how they source their 'food' for these feasts, whether it's through hunting humans or some other means. And the light novel format might make it more accessible with elements of adventure, mystery, and maybe a touch of romance thrown in if there are relationships between vampire and human characters.
The best chapter pointer here is Chapter 86, "If you don't welcome me, why should I stay?". It opens with After over an hour of fuss, it was finally time to eat. and closes on But then her expression became resolute and arrogant..
The best chapter pointer here is Chapter 49, "Mysticism Girl Jiang Li". It opens with My phone!!!" Jiang Yan's roar echoed continuously through the mountains in... and closes on Thinking this, Jiang Yan marched forward, pulled Jiang Li down from her....
A practical answer is Chapter 70, because it turns the idea into a concrete scene. The chapter opens with So, under the curious gazes of everyone, Jiang Yan strutted up with his..., adds pressure through Back at the airport, He Yun hadn't even greeted her., and ends on He Yun was also surprised as.
Chapter 49 is the strongest chapter-level answer because it starts from My phone!!!" Jiang Yan's roar echoed continuously through the mountains in... and follows through on Thinking this, Jiang Yan marched forward, pulled Jiang Li down from her....
A practical answer is Chapter 46, because it turns the idea into a concrete scene. The chapter opens with Upon hearing this, everyone but Jiang Li perked up with high alert., adds pressure through There must be some mistake with the crew's calculation, I demand a..., and ends on Did you calculate.
A practical answer is Chapter 53, because it turns the idea into a concrete scene. The chapter opens with Night had fallen over Chixia Village, eerily void of any human sounds., adds pressure through How does she manage that?] [Now, I really think all the negative press..., and ends on Wait, did.
If you want the clearest chapter reference, go to Chapter 56. Early on, Lei Shen originally had no idea about the trending topics on Weibo.; later, the chapter leans on He had been busy renovating his studio for a while and hadn't even had....
The best chapter pointer here is Chapter 48, "All the Bitter Teas Have Been Taken Away". It opens with He Yun felt guilty for initially ignoring Jiang Li on purpose, and with... and closes on Besides, everyone's phones will be replaced with special smartphones....
The best chapter pointer here is Chapter 100, "Ominous, there might be a bloody disaster!". It opens with The barrage was about to die of laughter. and closes on Her eyes flickered slightly as she grabbed the hand..
A practical answer is Chapter 72, because it turns the idea into a concrete scene. The chapter opens with Jiang Yan was still griping when suddenly a fair hand reached out beside..., adds pressure through [HAHAHAHAHAHA, this is the first time I've seen Director Sun speechless.]..., and ends on.