Transmigrate inside a Web Novel as a Side Character. - Chapter 6 - 0 Soul Pact.

... hat came out from Soma's mouth made the demon woman's brows twitch.

Soul pact was a type of magical contract that would bind part of the person soul who made it. The contract had an absolute rule over the content, and if one of the persons who made the contract broke the agreements, or one of it if there is a multiple agreement that was established, with their soul on the line. They will receive severe punishment and even death.

Soma had nothing left in his hand, and could only m ...