Wow. If I had to describe this anime in one word, the word is EPIC. The story is filled with psychological plots on how it all started. Then as the show goes on, more and more is revealed on what really occurred on that fateful day, the reason everything happened.
It takes place on a futuristic era, set on 2039. Humanity had encountered a strange virus that crystallizes a person. In 2029, when the virus spread throughout Japan, a multinational corporation called GHQ helped Japan and was paid back by their freedom. The story is about a 17-year old guy, Shu Ouma, who gained the "Power of the Kings." Shu was a normal High school student until he met Inori Yuzuriha, a girl from a band named EGOIST, and was a member of a rebel group. He falls for her and reluctantly joins the rebellious group who call themselves "Undertakers" or "Funeral Parlor."
The "Power of Kings" gives Shu an incredible ability. To draw out people's hearts as a weapon. They are called voids. Human heart that takes shape into the person's fear or personality. And Shu has the ability to draw it out and use it.