The series focuses on Ian Hasumi, a timid boy who sees fairies which are invisible to normal people and who is stalked by a vengeful spirit named Tokage. His mother left before the start of the series and as a result, Ian's father burns off the wing marks on Ian's back to prevent him from doing the same. Rin, Ian's abused childhood friend and secret "crush", returns to the city where he lives. Later, Ian accidentally stumbles onto the scene of a murder; after seeing a man named Kaito retrieve a cube from the victim's body, he follows Kaito back to his antique shop, where Kaito gives him Tokage's fairy cube—the contained spirit of a fairy. However, as a result of being manipulated by Tokage, Ian's father kills him. Tokage then possesses Ian's body and takes over his life, including romancing Rin. As a spirit, Ian goes back to Kaito's shop and after a trip through the Otherworld with a small but vicious fairy named Ainsel, is given the replacement body of a young boy. Ainsel agrees to aid him in his quest to regain his body. (Source: Wikipedia)

Volume 3 includes the unrelated oneshot Psycho Knocker:

Ashina Tomo is your average school girl who somehow constantly has terrible images of a train accident. One day, on her crush’s birthday, her best friend brings her to an isolated print club machine which is rumored to allow prayers to come true. What would happen when your prayers come true, but not the way you want them to be? By a cursed print club machine nonetheless.

(Source: M-U)