2channel

2channel (2ちゃんねる, ni channeru) or simply 2ch or 2chan, is a simple kind of Internet forum that does not require registration.

Plot
It first appeared in Chapter 37, or Episode 6 in the anime, where people started to mock and trolling Shishigami's parents, Shishigami got angry after his mother's death because of the intense pressure and sadness by the journalists and the internet trolls. Then Shishigami decided to use his cybernetic powers to search through 2chan, then after finding ID:Rs6evso's comment, he was angered after seeing that he's the one who send Shishigami's parents house address and photos, then he decided to contact him and killed him by shooting him through his computer screen, then one by one, every trolls on 2chan, was shot dead by Shishigami.