The series focuses on the forbidden love between the Angel Rin and the Human Miku Crynpto, who aren't allowed to be together because of their race and gender. Knowing this, Rin meets with a demon and exchanges one of her wings to become human.
The angel Rin has fallen in love with the human Miku Crynpto. She knows they can never be together becuase of their gender and race, so she trades one of her wings to transform into a human male. With her new body, she takes the name Len and seduces Miku. However Kaito has come to punish Miku for an unspecified crime and kills her. Rin finds Miku's corpse and trades her other wing to ressurect Miku, but dies as a result. In the end, Rin narrates that once Miku's feelings for her die away, she can return to life.
This song tells the story from Miku's point off view. She knows that she had pushed away the person she loved the most, yet she couldn't remember who that was. On the day of her wedding, she meets a man named Len and runs away with him. Although she loves Len, she feels that it isn't right and it hurts her. Later Miku is shot by Kaito and when Rin trades her wing for Miku's life, she recalls who Rin was, but it's too late as without her wings, Rin dies. Although heartbroken by her lover's death, Miku believes that if she keeps loveing Rin, they can see eachother again.
This song tells of the war that took place over a thousand years ago. Kaito, the angel queen Lily and and a green haired angel(Mikuo) fought a demon and banished him to the earth. However after the battle, the green haired angel and Lily vanished, presumably falling to earth themselves.
A novelized version was published on September 24, 2012, with much more characters. A book signing was also available with Hitoshizuku-P and Suzunosuke attending on September 29. A book trailer can be seen here.