[scififan]

So, Mio learns about date and her name from Shin. Mana's best friend is Kotori's mother. Then, Kotori should call Shin uncle instead of big brother.

Spoiler for not sure what to react:

The situation reminds me about J.C. Staff used to twist plots for novel to anime adaption. In one instance, Majutsushi Orphen, Azalie killed Childman and turned him to her fetus. For another instance, the ending of Angel Sanctuary also has killed turned fetus moment. Maybe it is just a nonsense artistic expression.