First Encounter with Shiro
On the battlefield, Aina fought Shiro Amada in a Mobile Suit battle that eventually led them to a sunken Magellan battleship. Despite being on opposite sides, the two realize they must work together in order to survive. As they cooperate to return to the surface, the two start to bond, with Aina giving Shiro her pocket watch to replace Shiro's watch after it was smashed.
Meeting Shiro Again
Returning to her base on Earth, Aina test pilots the massive Apsalus I Mobile Armor designed by her older brother, the head of the Apsalus Project, Ginias Sahalin.
Aina would later encounter Shiro again during the 08th MS Team's attempt to capture the Apsalus II. As the mobile armor as was retreating Shiro latched onto it with his Gundam. Aina tells him to stop, as such an action will likely result in both their deaths. Recognizing the voice as Aina's, Shiro attempts to make contact with her.
Eventually, the Apsalus II gets sent crashing into the mountains below during a snowstorm. As they fall, Shiro proclaims his love for Aina while attempting to halt the Apsalus II's fall. He succeeds, saving both of their lives.
Once again together, the two begin to open up about their love for each other, with Shiro giving Aina her watch back. The two are then both rescued by their own sides. Faced with her possessive brother, Aina lies about her relationship with Shiro, telling him he was killed. However, Ginias reveals he is aware of her relationship due to a recon photo taken right before her rescue, In addition to her having the demeanor of a woman in love.
As the Federation continues to attack the final Earth Zeon base at the end of the series, Aina and her brother pilot the now completed Apsalus III to cover a Zeon med-evac transport's escape during a temporary cease fire. However, Ginias chooses to attack during the launch, prompting the Federation to shoot down the transport. After Shiro shows up in his damaged Ez8 Gundam, Aina tries to convince Ginias to surrender, but her brother refuses and shoots her instead, causing her to fall out of the cockpit. Luckily, Shiro catches her with his mobile suit and the two later find out that Aina was saved by her pocket watch, which stopped the bullet. Aina then sides with Shiro to stop Ginias and destroy the Apsalus III, deciding that killing Ginias is the only way to stop the fighting. Co-piloting the Ez8 with Shido, the two manage to bring down the Apsalus III by destroying its cockpit, though not before Ginias fires one time, destroying the Federal Forces mobile battleship and seemingly killing both Aina and Shiro.
However, Aina and Shiro in fact survived and traveled to the mountains and start a life together away from the war that had been forced upon them. They were eventually found by Kiki Rosita and Michel Ninorich, who discover that Aina is pregnant with Shiro's child.
Principality of Zeon