Shiraishi, then 30 years old, enticed his victims, predominantly young women aged between 15 and 26, through social media outreach on Twitter, now rebranded as X. He manipulated these individuals by claiming he could help them end their lives, sometimes offering to die alongside them. His Twitter bio included a chilling invitation: “I want to help people who are really in pain. Please DM me anytime.”

The heinous acts were revealed in October 2017 when police discovered dismembered body parts in the city of Zama, near Tokyo, while searching for a missing person linked to the case. The discovery of nine bodies hidden in coolers and toolboxes within Shiraishi's apartment drew intense media coverage, depicting the home as a "house of horrors."

In the judicial proceedings, prosecutors pushed for the death penalty, while Shiraishi's legal team argued for a lesser charge of “murder with consent,” maintaining that the victims had consented to their deaths. However, Shiraishi later contradicted their defense, asserting that he killed without any such consent. His trial sparked public interest, and hundreds attended the verdict hearing in December 2020, leading to his death sentence.

The aftermath of these violent acts also led to Twitter altering its policies, instating a ban on content promoting or encouraging suicide and self-harm. For those experiencing emotional distress, several organizations offer support and assistance, with access details available in Japan and the UK.