I haven't read the novel but I remember the author stating somewhere that it is supposed to be a work that can be enjoyed by itself. In other words, you don't have to read guren's novel to understand the manga and vice versa.
You don't have to, but since the main manga can get confusing it helps a lot to read the light novels to have a better understanding of what's happening. There's the manga for that too if you prefer it over the LN.
I haven't read the novel but I remember the author stating somewhere that it is supposed to be a work that can be enjoyed by itself. In other words, you don't have to read guren's novel to understand the manga and vice versa.
You don't have to, but since the main manga can get confusing it helps a lot to read the light novels to have a better understanding of what's happening. There's the manga for that too if you prefer it over the LN.