Um. This one's a puzzler; Otsu Ichi has mentioned that he's a big fan of traditional mysteries, with their endless boring explanations of ludicrously involved deductive chains no actual human would bother with (we have this thing called intuition which tends to skip a few pointless steps).
He occasionally tries to write them himself, but doesn't seem to be very good at it. He likes them too much, or something; the moment he tries to write a mystery he starts writing the sort of flat, cryptic non-entities that populate most mysteries - for a writer so good at sketching strong characters in his regular work, it's baffling how something like Closet, where you know nothing about the lead, and nothing about the detective other than "she has pale skin" which he keeps repeating, like it will help us care.
And while the parameters of the mystery did shift nicely at one point in the middle, the logic ultimately failed to add up, unless I was just past caring and missed a bit. I mean, we've proven how the killer left the room, so how does that lead back around to him still fucking hiding in the closet?
The most entertaining thing about this was that I totally misread the katakana for the victim's name, Ryuji. Everything was quite a bit stranger when I thought he was Luigi.