A young woman is incarcerated in a women's prison, where she is assigned a cellmate who is a serpent-like being, a snake woman. The snake woman imposes a series of trials that the girl must endure and overcome, and together the two of them attempt to break out of the prison. The story follows their tense relationship and the dangerous obstacles they face, with the outcome of their escape effort left uncertain. The manga is an adaptation of a Vocaloid song that accumulated over 17 million views on YouTube, with the original song's creator personally overseeing the story adaptation. The narrative blends psychological suspense with the unique dynamic between a human inmate and her inhuman partner in confinement.