Socialphobia

Socialphobia is a 2015 South Korean mystery thriller film starring Byun Yo-han, Lee Joo-seung, and Ryu Jun-yeol. It was co-written and directed by Hong Seok-jae in his directorial debut, based on a real-life story that explores the social issues within internet culture among the Korean youth of the 21st century.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.