 If you liked
Brigadoon: Marin to Melan
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 ...then you might like
Dead Dead Demons Dededede Destruction (ONA)
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Both are science fiction series involving an alien invasion, war, and international politics, featuring adolescent girls and a slice of life vibe that juxtaposes its grand scale.
Though Brigadoon is more action-based and generally less realistic, while DDD is more drama and slice of life based.