From Viz:
Based on a true story. San and her friends are recruited as assistant nurses in WWII Okinawa. In cave hospitals of carnage and relentless loss, they endure as war strips away their innocence.
1 Volume (Complete)

I'm really glad the art style is not the realistic type. Otherwise, I might lose courage to finish it.
I love how this manga (consisting of 15 chapters) directly captures the terror of WW2. Without much introduction, we directly went into the bomb raids, the girls who became nurses, the dead bodies, hopless and horrendous situations, and all. After all, that's how war is. We try our best to live, but we never know if we (or anyone) will ever see tomorrow, even the end of the day.
You don't get slammed by what people had to live through but it creeps up until you are flooded by its emotions. It packs a wallop within a single volume.