Yokokuhan

Tokyo Police Department's Cybercrime Division is headed by the young, brilliantly ruthless Yoshino Erika. Her track record has been solid, but when a new threat appears online, it starts making all the headlines. A man who goes by Shinbunshi, because of the newspaper mask he wears, begins acting as a vigilante of justice. His message is simple: he can see what is wrong with society right now and although he doesn't have the power to change it, he can help the frustrated citizens release their pent up anger from the crimes that go unpunished like people treating others like trash, corrupt government pushing their weight around and other issues the typical person has no control over. Although it starts relatively harmless, it quickly snowballs out of control thanks to the power of social media and the Shinbunshi becomes an overnight internet sensation with the severity of the crimes exponentially increasing.

(Source: MangaHelpers)