With The Mantis, Kōtarō Isaka evolves while still remaining in the same world of weird assassins (which he shouldn't have to, the references to Bullet Train and Three Assassins calling too much attention to themselves). He's gone from a big cast, to three main characters, to a single one(Ish), and this one feels like it's about something other than karma/luck. Kabuto is killer on the spectrum, always analyzing situations too deeply, especially at home where he is deathly afraid of his wife's moods. He's trying to get out of the business and do what's right for her and their son, but the retirement package in this business is a bit... lethal. So what can we do. Of course, even if we're privy to his thoughts, we may also interpret the wife's reactions as completely normal. But the mistrust of the assassin's world pervades everything, a world of traps. It's really about doing accidental harm, and the consequences of our words and actions on others, even when our intentions are good, even if we didn't mean it and lashed out, and the sort of web of incidence that springs out of that (converging on the themes of previous books). The wife hurts Kabuto without meaning to, and he hurts his family even as he protects it, and there are loads of other aggregate examples throughout, including a key story about the preying mantis that lends the novel its title. I'm unsure about the third act style choice (a switch from third to first-person voice), but it works fine. All in all, Isaka's most mature work, if not his cleverest.