The mental growth of Yui Kamio (Yui in Black) gets stalled when the chain of Sanzo ties her hair
Yui had the chain put on her in the 5th grade. Since then it has been stated by Nao that the chain sporadically comes undone which lets loose the Yui in Black personality who would cause such a disturbance that Yui and Nao would have to transfer schools.- In chapter 7, after chasing Yui in Black around Teiyo Private Academy who was in very risque attire, Kiito worriedly chastises her for doing so and wonders aloud if she is a little kid.
- In chapter 9, Yui in Black while pretending to be Yui in White is unable to read English even though in chapter 1 Yui in White can read English. Black!Yui admits that she hasn't been in school since 5th grade.
More characters from the author's previous works will make an appearance
