ASSOCIATE PROFESSOR AKIRA TAKATSUKI'S CONJECTURE - NOVEL (2023) DIGEST-SIZED NOVEL #3

'The difference between damnation and celebration is paper-thin. At the same time, Takatsuki and Naoya learn of the urban legend about ''Library Marie''. Apparently if you solve a hidden cipher in the library collection, you'll be cursed. ''The unlucky letter and cursed cipher.'' Upon investigating the legend of a demon god in a village, in a grotto they find a skull with a hole in it. Soon after, Takatsuki is plagued by unexpected suffering. How will Naoya help him out of this one?!'