If the way Kiyoshi Mitarai decodes Heikichi Umezawa’s so-called “Azoth” plan—and how the studio’s sealed-room puzzle and nationwide alibis all resolve into a perfectly logical solution—made you grin, you’ll love the pure puzzle-box of The Decagon House Murders. Like the family charts and police documents in The Tokyo Zodiac Murders, Ayatsuji lays out floor plans, suspect lists, and timed movements on a secluded island, daring you to solve the killings before the final reveal.

That late-game turn in The Tokyo Zodiac Murders—when the dismemberments, the astrologer’s letter, and the decades-old cold case click into a single, shocking answer—has a spiritual cousin in The Devotion of Suspect X. As in Shimada’s novel, every tiny detail you took for granted is weaponized; when the truth lands, you’ll rethink earlier scenes the way you likely re-read Umezawa’s testament and the 1936/1979 timelines after Mitarai’s solution.

If the embedded artifacts in The Tokyo Zodiac Murders—Umezawa’s written “confession,” police reports, and clippings—hooked you, The Aosawa Murders takes that dossier feel even deeper. Through interviews, memoir excerpts, and transcripts revisiting a long-ago mass poisoning, Onda builds the same archival texture you enjoyed when piecing through the Zodiac case materials alongside Kazumi Ishioka and Mitarai.

The way The Tokyo Zodiac Murders toggles between 1936 and 1979—filtering the crimes through time and fresh eyes—finds an echo in Six Four. As with the Zodiac cold case, a historic 1989 kidnapping ripples into the present, and shifting timelines slowly surface buried truths. You’ll get that same slow tightening as new documents, old statements, and official stonewalling align into a devastating picture.

If you were propelled by Mitarai’s single-minded push to crack the sealed studio, the scattered-body conundrum, and the alibi knots, The Honjin Murders offers another ruthlessly goal-focused challenge. From the moment a newlywed couple is found slain in a locked room, the narrative barrels toward the how-and-who with the same crisp momentum you felt as the Zodiac investigation zeroed in on the mechanics behind Azoth.