Aoki Hagane no Arpeggio: Ars Nova, Girly Air Force Recommendations
Technologically advanced weaponry of unknown origins threatens the safety of the earth, and the only ones who can fight them are similarly technologically advanced weapons controlled by super AIs that have taken the form of cute girls who have taken a liking/bonded with the protagonist.
One is the air force and the other is the marines.
In both series, humanity faces a threat and is forced to use parts of the enemy to create defense weapons.
In Girly Air Force, there is girls who represent planes, in Aoki Hagane no Arpegio, there is girls who represent boat.