 If you liked
Uragiri wa Boku no Namae wo Shitteiru
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 ...then you might like
Karneval
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Both have a great art. Both are about a group of bishies and one girl who live together in a clan/organization and fight in pairs against demons/monsters. The main boy is very naive and before being a boy he previously had another form (girl/animal). Also his best friend is on the enemy side.