 If you liked
Shinigami wo Tabeta Shoujo
|
 ...then you might like
Karin wo Idaita Shoujo
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From the same author, in the same universe but each story taking place on a different continent. Both stories are quite similar since they're "realistic" harsh war stories with a merciless powerful young girl for MC.
Karin wo idaita Shoujo is a bit more light-hearted than Shinigami wo Tabeta Shoujo.