Signal (JP) (2018)

In the shadowy realm of law enforcement, Kento, a self-taught criminal profiler, emerges from a web of personal tragedy and mistrust. Haunted by the unsolved murder of a childhood companion and his own brother's mysterious suicide, Kento's faith in the police has crumbled to dust. Armed with a razor-sharp mind, a keen eye for detail, and a profound understanding of the criminal mind, he embarks on a solitary quest to unearth the veiled truth behind his brother's untimely demise. Stumbling upon a ghost from his past, Kento recognizes the woman who had ominously vanished with his childhood friend a decade and a half ago. Despite his attempts to alert an indifferent police force, the case languishes in the twilight zone of unsolved mysteries, teetering on the brink of oblivion as the investigation window nears its close. Suddenly, an abandoned receiver crackles to life, echoing with the voice of a fellow detective entwined in the same twisted case. Guided by these spectral instructions, Kento unearths a skeletal testament to a long-forgotten crime. As he converses with the enigmatic detective across the airwaves, he comes to a chilling conclusion - his newfound ally is a voice from the past, ensnared in a timeline that's not his own.

Signal (JP) is a crime show featuring Kentaro Sakaguchi and created by Kim Eun-hee.

Signal (JP) is currently streaming for free (ad-supported) on Rakuten Viki and it's also available on Rakuten Viki.