Isaka, the eldest member of the antagonistic Shichisei group, possesses grey hair and grey eyes. His primary power is conjuring a large, cubic protective barrier he considers unbreakable, which forms his core combat tactic. This barrier defends against most attacks and can shield multiple allies simultaneously, proving highly effective in group engagements.

Isaka exhibits significant arrogance and overconfidence, particularly regarding his defensive prowess. He prefers strategic positioning over direct combat, relying entirely on his barrier for protection. This confidence is shattered when Keisei Tagami sacrifices himself to destroy the barrier, an event that profoundly impacts Isaka and exposes the vulnerability he dismissed as impossible. The destruction causes him significant distress, revealing his deep psychological reliance on the ability.

Within the Shichisei, Isaka holds a leadership or senior advisory role. His actions and defensive capabilities support the group's objectives, though his specific motivations or personal history remain undefined. His defeat occurs during the confrontation where Keisei's self-sacrifice overpowers the defensive cube, leading to his elimination.