Kaei stands as a prominent antagonist in the Experts of Justice's conflict with the BF Organization, operating as a key member of the Shizuma Drive faction. He functions as a master strategist, consistently planning steps ahead of his opponents and manipulating events from behind the scenes rather than engaging directly. His methods rely heavily on intelligence, charisma, and persuasion to recruit followers and orchestrate complex schemes aligned with his goals, even when those goals conflict with others' interests.

A significant traumatic event shapes his background: the loss of his entire family in a catastrophic accident. This tragedy left him emotionally damaged and fueled an obsession with acquiring power and control. These motivations drive his actions, positioning him as a formidable adversary focused on overcoming perceived obstacles through extreme measures.

Kaei demonstrates analytical prowess and sharp observational skills, often withdrawing from direct social engagement to assess situations from a distance. He exhibits self-sufficiency and reluctance to rely on others, stemming partly from underlying insecurities about perceived inadequacy. His powers include superhuman abilities, with their exact nature unspecified beyond their tactical application in service of his strategies.

His narrative trajectory culminates in the failure of his meticulously crafted plans. Daisaku Kusama, the primary protagonist, ultimately thwarts Kaei's efforts, leading to his definitive downfall within the OVA series.