Chapter 55 of Hell's Paradise: Jigokuraku.
Rien sends a wave of Tao towards Chōbē and causes him to sense that he is dangerous. Rien claps his hands in fascination, seeing as how Chōbē achieved hybridization from being infected by the Waidan flower in the pit. He then decides to examine him further and sends a destructive Tao ball his way. Chōbē dodges and enters his transformation in full control by suppressing the vines inside him. He manages to overwhelm Rien but is finding it difficult to keep the vines from taking over his body. After piercing Rien's tanden, Chōbē destroys his body and prepares to end his transformed state. However, Rien suddenly appears behind Chōbē, revealing that he has destroyed one of his many clones he brought along. After seeing Chōbē unleash the Tao of the Waidan flower, Rien expresses his satisfaction and decides to take him back to the palace. Chōbē tries to attack but is unable to resist the effects of the vines. Rien then uses a Tao palm strike to knock Chōbē unconscious. He then dreams of his desire of not making the same mistake as his father by abandoning his brother. Later, Chōbē wakes up tied to a bed and sees Rien as a female. Rien explains that she finds Chōbē to be the final key to completing her research and wishes to understand his Tao cycle better through Bochu Jutsu.