Spiral - Suiri no Kizuna
Spiral: Bonds of Reasoning / Spiral ~ Lines of Reasoning / Spiral ~ Suiri no Kizuna

Two years after brilliant detective Narumi Kiyotaka disappears, his younger brother Ayumu is drawn into a mystery surrounding the Blade Children. Kiyotaka leaves behind his wife and brother, along with a cryptic message about them. When Ayumu is falsely accused of murder, he begins investigating the Blade Children and their connection to his missing brother. The case brings him closer to the mystery Kiyotaka left unresolved.