Spiral: The Bonds of ReasoningSpiral: The Bonds of Reasoning.

Spiral: The Bonds of Reasoning (Japanese: スパイラル〜推理の絆, Hepburn: Supairaru: Suiri no Kizuna) is a Japanese manga series written by Kyo Shirodaira and illustrated by Eita Mizuno. It was published by Enix and then Square Enix in Monthly Shōnen Gangan from 1999 to 2005 and collected in 15 bound volumes. The series focuses on Ayumu Narumi and his efforts to solve the mystery of the Blade Children, cursed geniuses with cat-like eyes lacking a seventh rib bone.