This is a good locked-room mystery with an interesting detective who, my manga-reading daughter tells me, she felt may have been, in part, an inspiration for the Death Note detective, L.
I liked the metatextual discussion of locked-room mysteries by the narrator & by the characters, which bore directly on the story itself: very clever. The setting and cultural insight was interesting, too.
I've ordered the second in the series from the library 😊