Agito is an Ancient Belkan Unison Device without a master—until Zest and Lutecia rescued her from rogue scientists who were experimenting on her. She has no memory of her past, which makes the whole thing even more mysterious. She's got this bitter rivalry going with Reinforce II, basically because Rein has a "Meister" and Agito doesn't. She was convinced at first that Vita was actually Rein's master, which only made things worse.
She's pretty casual with Zest and Lutecia, calling them "Boss" and "Lulu" instead of using their real names. Unlike Zest, Agito actually warned Lutecia about Scaglietti—told her he only wants Lutecia so he can experiment on her. That's the kind of straightforward heads-up that sticks with people.
When it came to finding Agito a Lord, Zest thought Signum was the perfect fit. Signum was a true Ancient Belkan Knight, and after Zest died, Agito accepted the union. Their synchronized unison mirrors what you see with Reinforce and Hayate—they get a major power and appearance boost when they combine. Even by the epilogue, Agito's still got that competitive edge with Rein, their rivalry far from settled.
Content compiled by AnimeList.moe from publicly available sources.
