When the story was about how he was recovering from guilt, it's pretty great and a lot of people can relate to that feeling even if they never had done something as extreme as killing someone. We want to see more of this recovery along with the girl and see how they can support each other, but this arc in particular has been leaning towards the trauma, the thing we wanted for the guy to move on from. I guess this is confronting the trauma in a sense but it's executed with an overabundance of plot twists though I'm glad he knows that to dumb it down the kid just wants Shiika to suffer and this is more centered around Shiika than Kazuma.
For me personally, it's hard to sympathize with Shuusuke, he treats his trauma by affecting the people around him outwardly because inwardly, he sees no chance of redeeming himself. If Kazuma can talk to him, one-on-one, in the hospital after this and make him realize there's still hope, the author can still save this