Serialised on the website Comic Pash Neo; demographics are a little hazy but Bookwalker reckons it's shoujo/josei.
This series comes up in conversation around Shukufuku no Ceska on social media, probably because of their similar demographics and the focus on language/communication (although Prizrak is much less complicated in that regard!).
Erde ("the land") is thinly veiled Germany; Morye ("the sea", roughly - I know no Russian I'm afraid and apologies if that's not the right Romanisation, I don't think it's quite right grammatically) is thinly veiled Russia. I'm never entirely sure how I feel about the way manga sometimes trades in the European iconography of the World Wars for entertainment - it can border on fetishism at times - but I think there's enough going on here that's more meditative rather than exploitative, particularly based on what I've read of the rest of the series to date.