 If you liked
Rokka no Yuusha
|
 ...then you might like
Date A Live III
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Both involve identifying a shape shifting impostor that is hiding among the main group of characters, with some mystery and psychological elements. While in Date A Live III it's only the first arc, and one should probably watch the rest of the series before it, the concept is the main driving force in Rokka no Yuusha, getting more thoroughly explored. Both shows also involve a lot of romance, with some pretty cool characters, and action, with a lot of interesting powers and abilities.