Granblue Fantasy, Volume 4 (Granblue Fantasy #20-24)

Gran and his crew find Tzaka the Great in an old factory, but the archduke is not the kind-hearted man that Io once knew. Obsessed with the idea of avenging his kinsmen, the archduke uses Lyria's power to activate the slumbering giant, Colossus. When the Black Knight and her allies get involved, Gran and his team must race against the clock if they want to get Colossus and the archduke out of the Arsenal... alive.