Cheon Daiyu, the Ninth Princess of the Demonic Cult was the illegitimate child of the Cult Leader, making her the target of bullying and ostracization by his many wives. Confined in the Black Jade Palace, Daiyu discovers a strange violet marble in the forest one day after running away.

'You must swallow it.'

Daiyu ends up eating the strange marble she found accidentally but it turns out to be carrying a fragment of the Fourth Heavenly Demon, Cheon Haoran's soul. The once feared Lord of the Demonic Cult materializes in front of Daiyu as a spirit and makes his decision.

'I'll make you the strongest Heavenly Demon in the Cult's history. After me, of course.'

The strange relationship between the young princess and the most revered Heavenly Demon of all time begins! It is time for the Central Plains to witness the rise of Daiyu's sword.