noun
Internet police
Refers to individuals or groups who monitor online behavior and enforce rules, often in a self-appointed or vigilante manner. Can be used seriously or sarcastically.
彼はネット上で荒らしを見つけるとすぐに通報する、いわゆるインターネットポリスだ。
He's a so-called Internet police, reporting trolls as soon as he finds them online.