Ira becomes fixated on Touge, the brother of her best friend Saeko. Despite the fact that he's a womaniser, she thinks that he's gay. Saeko encourages the friendship, not telling Touge the full truth until it's too late. She begs him to play along in order not to upset Ira's already tentative mental health. The ruse goes a little too far and Touge agrees to marry Ira. After the wedding, Ira insists on on meeting Touge's 'boyfriend' to explain the situation. Saeko arranges for Ōgami, who is in fact gay, to play the role of boyfriend, even though she herself has a crush on him.
Intercut with the story are scenes where Ira dreams of a beautiful but deadly creature visiting her in the night and threatening to eat her. As her mental health worsens, these scenes become more intense until they are interfering with her waking life.
A few of the plot points seemed unrealistic to me. The fact that Ira's parents agree to let her drop out of school and marry seems a bit unlikely. It also grated with me that Ira decides to run away and live with Ōgami's boyfriend, despite knowing that he's a perpetrator of domestic violence. Again, her parents allow this to happen.
The ending seemed a bit disjointed. The ending of each character's story is told separately whereas they could have been better integrated. Depite these points, I enjoyed the story. The unpredictability of Ira's actions, coupled with Saeko's unsuccessful attempts to help her, give the story interest. The ending, whilst generally positive, isn't a sickly-sweet 'happily ever after'. I'd like to read other manga by the same author.