From The Register:

A local Japanese government agency dedicated to preventing organized crime has apologized after experiencing an incident it fears may have led to a leak of personal information describing 2,500 people who reached out to it for consultation.

This is a particularly unfortunate hack given that organised crime gangs have something of a reputation for seeking revenge on anyone whom they might regard as disloyal or a threat to their impunity.

It happened as the result of one of the classic phishing exercises:

A staff member was using his work computer when he received a popup warning him his computer had been disabled and to call a number for support. He did so, followed the instructions, and unintentionally gave criminals remote access