Ludwig's background of a serial killer is exactly that, a background. That doesn't mean he stops killing, no, he will kill a lot of people, but the first chapters will be lacking in this regard, he also won't go around massacring villages for fun, in his opinion, killing is a very high profession. And if he massacres, he does it for very good reasons, such as profit. Still, it will be lacking in this regard in the first few chapters, as this is going to be a longer novel. I hope you guys can see the potential and still support me, but I can understand if a few would rather wait till later.
The world we are in is a Cultivation World, up to the beginning of Chapter 4, it's his background in urban modern earth.
Why are the first chapters slow and have few killings?: this is the clan building aspect of this novel, you can see this when you look under the tags as 'kingdombuilding', which is the closest tag to clan building. He will build his branch to be his foundation in his future endeavours. After all, not everyone is born with a golden finger, and Ludwig has to make the best of his situation.
There is a romance sub-plot, I won't describe it deeper than this, but there will be hints.
This is an accumulative novel, in which the world we see grows and is seemingly expanding as we read on, a lot of world building is done all around, you will see a lot of different things, but for this to happen, as one might guess, the novel will be longer and I hope readers aren't too disappointed that Ludwig doesn't rush into action all the time.
Lastly, this novel is in the same universe as more of my books (not all of them), but this will be a topic for much later, so you don't need to worry about this just yet!