Thanks to @rodan and the amazing Bookwalker Freebies thread, I found out there’s a promotion currently on Bookwalker (who would have thought), with lots of novels from Kodansha at 99 yen. Among them, 眼球堂の殺人 was already on my list (who knows where I first heard it), so I thought I’d watch a video about it first. Turns out this was Masaki’s very first video ever, and he introduces us to his favourite book 
Looking at the 99 yen novels, I also found 邪魔 potentially interesting, but I can’t find much info about it. There seem to be few reviewers compared to other books. And I’m also looking at 怪奇小説集, because ghost stories and Shusaku Endo. 