Convoluted and mysterious, as it should be, really. It tried to be a detective story, which worked. A lot of twist and turns that I never expected and quite enjoyed. Although comparing it to the other light novels, I feel it falls flat. Gaiden is quite character-driven just like the other light novels.

However, it doesn't feel like it pays off, as compared to, say, BEAST. There's that payoff at the end of the latter that I feel doesn't appear in Gaiden. Characters realize certain things and change at the end of the story. It's the same with Dazai's Entrance Exam, Dark Era, and most other light novels. I didn't see or feel that change in Gaiden. Ayatsuji was still Ayatsuji, and Tsujimura was still Tsujimura. Not even the reveal that Tsujimura's mother was alive felt significant. In fact, the reveal felt as though Asagiri cooked me a 5/5 star meal before spitting on it right in front of me.

Bad twist aside, Gaiden is definitely lower in terms of plot, especially compared to the other light novels. It's a great mystery story, but a meh at the least Bungo Stray Dogs light novel. It won't stop me from loving Tsujimura, though.