Rumi : Why...?

Rumi is troubled by the relationship between she and her little sister Miru, which she usually feel apart from her. The fact that Miru actually likes to be with Rumi, but she find it hard to express due to her introvert personality. Also Miru prefers to stay with Erina, who by her nature is a rabbit rather than a human. Don't bring it up in front of Rumi. Rumour goes that she's been working with Miriam, Pandora and Ashuri on a potion that can turn them into rabbits. People are afraid to go near Miriam's shop at night because of strange noises and flashes coming out from the windows. What's the purpose of their research?!