Spiral Suiri No Kizuna Episode 5

Narumi Ayumu lives in the shadow of his older brother's disappearance two years earlier. Now residing with his brother's wife, police detective Narumi Madoka, Ayumu is constantly preoccupied by the last words his brother spoke: Blade Children. As a series of mysteries arise, Ayumu uses his formidable detective skills to solve the crimes. But it is always the larger mysteries that continue to loom over him. Who are the Blade Children? Why did his brother disappear?