Watch Spiral: Bond of Reasoning full episodes online enghlish sub
Other titler: Spiral: Suiri no Kizuna
Synopsis: Ayumu Narumi’s older brother Kiyotaka, a renowned detective and piano player, disappears all of a sudden. The only clue Narumi has, are the Blade Children. Two years later a row of murders and incidents begin, relating to the Blade Children. Together with school journalist, Hiyono Yuizaki, Narumi tries to figure out their destiny.
More info: Myanimelist, wikipedia