Hikiko: The Descent

Yukari organizes a reunion for her elementary school class through social media after 10 years apart. At the event, she reconnects with Kiriko and Nico, and the three quickly bond over their shared resentment toward a group of bullies from their past. Driven by a desire for revenge, they create a website to expose their former tormentors, believing the authorities won't help them heal. They post videos of stalkers and other wrongdoers, gaining popularity and supporters. However, Nico and Kiriko soon spiral into more extreme acts of violence.
(Source: MDL)