Toaru Majutsu no Index: New Testament - Volume 14, Chapter 3: The Girls’ Desires and Their Intersection - Winner’s_“APPLE”.

What's the book about? It is about Demonic Cultivation!, If you cannot handle it, Please don't read it.Synopsis:When Song Wen killed the frail beggar who fought him over food and consumed his blood and soul, every cell in his body leaped with excitement. His spirit was exhilarated, and he realized then that his life would henceforth be filled with slaughter. For survival, for longevity, he would spare no effort, even if it meant creating mountains of corpses and seas of blood.

As a walk-on, he had been the mistress of his sugar daddy for three year. However, they only had met each other for a few times.
As a boss, his sugar daddy had tons of lovers.
The walk-on: The cake shop is the only thing I love in this world. Lovers? Never want one.
The boss: No problem. Nobody wants that.
Then, they fell in love with each other…
Shameless playboy x heartless rogue
1v1, this is not a decent love novel.

- Description from Novelupdates

Jin, a guy with no direction in life, through an unfortunate event gets his hands on a Hitman System. What transpired then was a struggle to escape the eyes of the cops while trying to complete the system’s missions. However, through a series of coincidences, he soon finds out that his parents’ death was not an accident. Read how he uncovers the veil that has obscured the truth from his eyes since childhood and finds out the darkness that hides under this veil. ‍

Hyde arrives in a doomed world with nothing but his body and fragmented knowledge of the future from a game he once played. He has no grand ambition—why try to save a world already destined to fall? Survival is enough.That is, until he discovers his sister is also transported into that world.However, only he hears the Melody of Nightingale and receives the power to survive.[You have established a connection with The Forgotten Hollow.]Awakening as a Resonant—an elite group with supernatural abilities—he is thrust into a conflict between two worlds. Armed with the authority of space and time, he vows to protect his powerless sister at all cost, even if he has to fight against the Mirage creatures, other Resonants, or even Gods themselves.