Castta met Klaus during the Paragon of Death's era.
He was the elder brother of Sayuri, now known as Supreme Warrior Sayuri, who serves as one of the headmistresses of the Heavens Academy in the Milky Way Galaxy.
Back then, their home was ambushed by the Heavens Court for sheltering an injured ally of the Paragon. Many died, while those who survived were taken away to rehabilitation camps, where they were supposedly reformed into people who would hate the Paragon.
Of course, the rehabilitation program was merely a front for selecting able-bodied men and women to become Heaven's warriors.
Castta was one of the lucky ones to be chosen... or perhaps one of the unlucky ones.
Regardless, he was selected and thoroughly brainwashed. Considering he was one of the most talented individuals of his generation, he rose through the ranks much faster than most.
