Spiral: The Bonds of Reasoning

It is a shonen-mystery manga written by Kyou Shirodaira and illustrated by Eita Mizuno.It had fifteen volumes and had two publishers in Monthly Shonen Gangen from February 2000 to October 2005. The series had an anime adaption containing 24 episodes but only featuring some of the manga chapters,with slight differences and it had an English dub too.

Plot
Two years ago Ayumu Narumi's genius brother disappeared without a single trace.The only clue was the "Blade Children",the last words he heard from Kiyotaka.Along with his new partner,Hiyono Yuizaki,Ayumu solves a number of mysterious all related to the Blade Children,who are discovered by their cat-like eyes and missing seventh rib.