She is Satan's Little Sister, and reunites with her formal pupil, Sebastian Michaelis. Ciel wishes to make a contract with her, but it seems Sebastian is against the idea, even though she can split souls. Rei Araesti, she obviously has some sort of connection with Ciel's favorite Butler, but Ciel doesn't know why he is so fond of her. Will Satan figure out that she's been making trouble once more and decide to take her away, or will Grell's jealousy lead her astray. But most importantly, is Ciel also gaining feelings from the strange girl?