I just wonder who is that unlucky ship girl that got sunk...
Let's see. That box-shaped turret narrow down to only a handful of ships, like, the Ayanami Class, Shimakaze, and Amatsukaze.
Oh, wait. Look at the arm, loos like she got short sleeved shirt. That said, we should dash out Amatsukaze, who has long sleeves and Shimakaze, who is sleeveless. Now we only have 6 possible victims left, let's move on.
The sleeve collar is blue, so I think we should dash out Ayanami and Shikinami, who has brown sleeve collar.
But... that's where I run out of clues. There still are 4 possible victim remaining.