When he was in primary schools, his older brother was a kind and admired figure. After witnessing his brother's mysterious death, Ryuhei is now a lively high school student who doesn't feel the nightmare around him. On the night he is bitten by the mysterious creature Tris, he has an unusual dream. A group of black-clad youths are battling a strange creature. Ryuhei, who is at the mercy of a mysterious phenomenon, finally sees the monster in real life in Shibuya.