Yes, it is quite popular. It has attracted a large number of fans both in Japan and internationally. Its unique premise of a reincarnated spider has drawn in readers who are interested in isekai and fantasy stories.
In this light novel, the protagonist finds herself as a spider and embarks on an adventure filled with challenges and discoveries. She has to adapt to her new form and the dangerous environment around her to make her way in the world.
The content of 'So I'm a Spider So What' light novel 3 is full of exciting adventures and new challenges for the protagonist. There are unexpected plot twists and character developments.
I'm not entirely sure as I haven't read it in detail. But generally, it might be about a character who decides to stop being a hero. This could involve things like the character being tired of the hero life, facing moral dilemmas in heroics, or having some personal issues that make them want to quit.