Looking for this manga

So all I remember was that there was this girl who wrote novels. She was really skinny and had a chubby manager. Later she got involved with the Gang because she was the guarantor for this guy who lost his money. The later one of the guys who is the collector and he started to have sex with her. They both fell in love with each other. I don’t really remember how it ended. But the chubby manager was with a girl who knew the male lead?