There is no System or any level-up progression in this novel. It is a mafia novel, not the type with harem, sex, NTR, and so on. It does include a love aspect, but the focus is on the core theme of the mafia along with drugs, money, murder, government corruption, and everything connected to crime.
So if you're looking for harem or a main character who fucks with everybody, this is not for you.
Also, this is not a lighthearted novel. There is a lot of blood, torture, tragedy, trauma, suicide, and death.
Please keep all of this in mind before you start reading. Thank you, and enjoy.