This is the first time I've seen anyone deus-ex-machina a complication to drive the plot, rather than a solution.
What am i supposed to feel? The random 'deaths' are to impersonal and immemorable to have an effect on the reader's perspectives/reactions to the story. If anything, there is a mismatch of expectations, where although the mangaka tries to make (potentially) killing people randomly a complication, the readers have not witnessed anything to suggest that such a reaction is warranted. Sure, killing people is bad, but there is no tie in with the story, no repercussions or otherwise
Mirror beasts? Investigate them? Or perhaps remove the mirrors?
Even though the MC is depicted as rational, smart, kind and cognisant of her predicament, all she does in trying to solve the problem is shutting herself in her room.
All-in-all its a poor premise with a poorer execution.
6/10