A notorious Exodus specialist and a formidable combatant who has earned the nickname "Black Southern Cross", we are first introduced to Gain Bijou as he is taken into custody inside the Siberian Domepolis. Gain's mission in the dome is to oversee a mass Exodus from the city by those wishing to flee the tyrannical oppression of the government in order to start their lives anew. With an appointment to keep, Gain makes his escape from prison, opting to take Gainer with him since the Exodus is about to start and the city's attention is focused on the big festival and popular idol singer Meeya Laujin. After stealing an Overman, which he has Gainer pilot, as well as taking the daughter of the Duke who controls the city hostage, Gain takes to piloting his Gotchko and demonstrates his formidable skills on the battlefield against the defending security patrols of the Siberian Railway.