Medical student Satou Masaki was separated from his big brother, Kagura Kyouichi and his little sister, Kagura Mika, due to their parent’s divorce.

A few years later Mika, who he has started talking to via the internet, asks him to check on their brother, who has stopped responding to her messages. When Masaki arrives at Kyouichi’s apartment he discovers his brother’s dead body covered with tattoos- four kinds of symbols and two spirals.

Misaki starts to investigate his brother’s death along with Houjou Ritsuko, his lover who is also a police detective, and his friend Suzuhara Natsune. As they get closer to figuring it out they encounter an onslaught of mystery and death.

What truth is waiting to be revealed to them?!

[Translation of synopsis from Getchu.com]