Gender Swap: I Can't Believe My Childhood Friend Is Still Here in World War I

(Originally titled “Fantasy World”) [World War I + Alternate History + No System + Wild Imagination + “Order Sickness” + A Certain Spiritual Kinship with the Cthulhu Mythos + Standalone] Odette, who grew up in a monastery, joins her childhood friend Durand in the fervent fight for France. But the enemies they see on the battlefield seem a little off… Wait, even their own side is acting strange. …Why has everyone changed so much? Why is this different from what the nuns, stories, and history told us? Which World War I is this, exactly? (I don't know why I'm writing this stuff. I'm just writing, one word, then two, then three. And by the time I realize what's happening, the story is finished. That's all.)