It seems that things have finally gotten serious.
From the look of Mirai’s past, I can understand why she feels that way. Besides her ability that allows her to manipulate blood, it seems that a spirit hunter adopted her. She was isolated from the family, but Yui decides to show Mirai the world around her and unfortunately, both girls ran into a Hallow Shadow and her friend got possessed, leaving Mirai no choice but to kill her.
To me, I don’t think it’s her fault since it was a near-death situation considering that she would have died if she didn’t do something. Not only that, she probably didn’t know how to release Hallow Shadow’s control over her without killing her. Still, pushing people away is probably not the best thing for her to do since she already have a hard time taking down a dream shade as seen in the first couple scenes in this episode without Mitsuki’s help. This basically proves that if she go and battle the Hallow Shadow alone, she might not make it out alive.
While this episode is basically a set-up for the big battle in the next episode with Mitsuki revealing some information about the Hallow Shadow, I felt that this show evolved into something different. This episode seems a lot darker than before, which makes me wonder how Mirai will develop from here. While she is somewhat ditzy and clumsy, I feel that she will become a capable fighter. Even so, I wonder how she is going to resolve her regret when Sakura whom looks exactly like Yui attacks her out of nowhere. We might find out that and more in the next episode and it looks like Akihito will get stabbed yet again.