Sai Argyle, Kuzzey Buskirk, Millialia Haww, and Tolle Koenig were all classmates of Kira in the robotics research. They were also residents of Heliopolis were brought into the situation with Archangel where they are nearly forced to become members of the military to keep from being charged with war crimes. They quickly take up positions aboard the battle cruiser, assisting the other officers and maintaining contact with the Strike Gundam in battle.

Sai has a soft spot for Frey Allster. They were both arranged to be together as younger children, and Sai is intent on keeping their early relationship alive.