Responses
I liked chapter 5. I wouldn't call it inferior to the works you mentioned either. I'd read my fair share of crazy psychological incest manga and this has one of the most interesting concepts out of them all. It might not have jarring scenes where one brother burns his face for the other, but I think that's better for this story. It feels more rooted in reality than Ogawa's work.
Ch 5 gave me similar psychological vibes as Asumiko Nakamura (though clearly not even close to her level). Also super reminded me of Ibitsu Na Kakera by Ogawa Chise and Deichuu no Hasu by Tamekou. If you enjoyed ch 5, I recommend reading these! They're both way better psychological incest BL.
Overall though, I was disappointed with ch 5. I think it had potential but with so few pages it fell flat. Would have liked to see it as a full volume so the characters, their motivations, and backstories could be explored further. It was also quite jarring sandwiched inside the main story which had a completely different emotional tone. Though I wonder if this was an intentional marketing decision.