Fleet Girls are girls who possess the souls of warships from days past. A new fleet girl Fubuki has come to their base, the Naval District. With her roommates Mutsuki and Yuudachi, she goes to see the bigger carrier girls.
Fubuki returns safely from her first mission. She'd love to be an escort for a carrier like Akagi, but she can't even sortie at her current level of training. The Sendai sisters offer to help her train.
After participating in training, Fubuki and Torpedo Squad 3 move on to the attack on W Island. The night before the mission, Fubuki's roommate Mutsuki reassures her and makes her feel better.
After Fubuki's hard work, Assault Group 5 is finally starting to come together. But Kaga is struck and badly damaged when she tries to protect Zuikaku from a torpedo. Shoukaku is added to the group in her stead.
Fubuki hears a message from the admiral from Nagato. His words inspire her to do her best and continue her training and studies. Mutsuki looks sad as her friend grows.
At last, operation MI has begun! With the admiral's orders in hand, the fleet girls prepare to attack. But Akagi is nervous, and has an awful premonition.
The fleet attacks Abyssal base MI. Despite their strength the forces seem unkillable. When they sink an enemy it just comes right back up again. Is there any way to win the fight?