I'm not entirely sure as there could be multiple main characters. But generally, there would be a protagonist who is summoned to the other world and is likely involved with the slave - summoning and magic aspects.
Typically, in 'isekai maou to shoukan dorei majutsu light novel', the main character is a person who is suddenly thrust into this new world. This character has to figure out how to survive and thrive in a place where summoning slaves and using magic are common. There might be a female lead character as well, who could be a slave or someone who helps the main character understand the new world's rules regarding slaves and magic. Additionally, there could be other important characters like a mentor figure who teaches the main character about advanced magic or how to manage the slaves more effectively.
A practical answer is Chapter 28, because it turns the idea into a concrete scene. The chapter opens with The next evening, Jiang Yan drove home seething with rage., adds pressure through Fuck, who's there, standing in the middle of the night scaring the shit..., and ends on Lili then kicked his.
A practical answer is Chapter 37, because it turns the idea into a concrete scene. The chapter opens with The barrage was suddenly filled with hahas, but the two guests present..., adds pressure through The moment her gaze landed on her, she couldn't help but pause., and ends on I look forward to.
A practical answer is Chapter 42, because it turns the idea into a concrete scene. The chapter opens with You've all met now, so this game is very simple," Director Sun said., adds pressure through Both trapped and rendered powerless by public opinion., and ends on As the plane hadn't taken off.
A practical answer is Chapter 48, because it turns the idea into a concrete scene. The chapter opens with He Yun felt guilty for initially ignoring Jiang Li on purpose, and with..., adds pressure through [Such a stark contrast on camera, five people feeling dejected, and..., and ends on Besides.
A practical answer is Chapter 51, because it turns the idea into a concrete scene. The chapter opens with Oh, okay." After uttering two syllables indifferently, Jiang Li bent down..., adds pressure through With this in mind, she looked up and scrutinized the worried faces in..., and ends on If I.
Chapter 53 is the strongest chapter-level answer because it starts from Night had fallen over Chixia Village, eerily void of any human sounds. and follows through on Wait, did this kid accidentally fall into the water?] [Help, this camera....
Look to Chapter 52 for the clearest answer. It begins with The village chief and the woman behind him exchanged a glance, "This..., keeps building through might not be a good idea, you guys are still filming, we don't want to..., and lands on And at this point, they might as well try a desperate.
Look to Chapter 62 for the clearest answer. It begins with Sitting on the edge of her bed, she pondered for a while before lifting..., keeps building through The moment the door opened, she saw her photographer with his hand still..., and lands on Jiang Li reached in, pulled out a piece of paper.
A practical answer is Chapter 61, because it turns the idea into a concrete scene. The chapter opens with Hahahaha, oh my god, Jiang Li's mouth is even more venomous., adds pressure through The man's expression darkened for a moment., and ends on A cold shower is pretty normal, right?.
The best chapter pointer here is Chapter 72, "Jiang Li Resembles an Early Capitalist". It opens with Jiang Yan was still griping when suddenly a fair hand reached out beside... and closes on Think about it." Jiang Yan fell silent..