Turnabout! Natose Cometh

Yume goes missing from the Kuonji household due to an argument with her sister Shinra. Ren and Natose go out to search for her, and more is revealed about Natose's past and the reason for her affection to Ren and Yume. It turns out that Shinra actually cares for Yume the most when she returns home, and it is revealed that the Kuonji siblings lost their parents since a young age. Shinra had to be strong in order to keep her family together, which caused her apparent emotionless state as a child.