DeathCord is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here. You are reading chapters on https://mangabtt.com fastest updating comic site. The Summary is
One day, Kyung-min, whose self-esteem has hit rock bottom from being Tormented/Bullied by his friends, suddenly receives an invite to ‘DeathCord’, a chatting room where you can kill people through voting. Anonymous death penalty vote in the chat room! Anonymous participants invited to the chat room are keen to kill people for their own reasons. However, one of the chat participants becomes the target of the death penalty, after that, the participants in the “DeathCord” chatroom start struggling to identify each other…A murder game that won’t end unless each other kills each other!