Spiral: The Bonds of Reasoning [TV]

Two years ago, Ayumu Narumi’s older brother Kiyotaka, a famous detective and pianist, disappears without a trace. Ayumu’s only clue as to his brother’s whereabouts is the phrase “Blade Children,” the only words Ayumu could make out in Kiyotaka’s final phone call. Now in high school, Ayumu becomes involved in solving in a series of murders and other incidents, all related to the Blade Children. Together with his school’s journalist, Hiyono Yuizaki, and the unwilling assistance of his sister-in-law, Madoka, Ayumu tries to figure out who the Blade Children are and what are their goals.
The Blade Children are the central mystery of the series, known only as cursed children that few know about and are being pursued by so-called Hunters. They are distinguished by their cat-like eyes (though a few lack this feature) and by missing the seventh right rib bone. As Ayumu investigates them, he meets Blade Children Kousuke Asazuki, Rio Takeuchi, Eyes Rutherford, Ryoko Takamachi, and Kanone Hilbert, and is tested in various ways by them. Those who meet him eventually conclude, some more reluctantly than others, that Ayumu does have what it takes to “save” the Blade Children, as they say Kiyotaka claims.
The anime series, which adapts the story through the sixth volume of the manga, compares the Blade Children to cuckoo birds, having been deposited in human “nests” to be raised, and suggesting that cuckoos go violently crazy toward the end of their lives. The manga continues the story, depicting Ayumu’s discoveries about the origin of the Blade Children, their relationship with Kiyotaka, and why his older brother thinks Ayumu might be their savior.
Some thirty years ago, a man called Yaiba Mizushiro was born with one rib missing from his right ribcage. Like Kiyotaka, he excelled at everything he chose to put his mind to. When he turned twenty-three, Yaiba started his own secret society, which swiftly grew powerful enough to manipulate world events. Citing boredom, Yaiba initiate