Hikari Daitokuji is B-ko Daitokuji's father and CEO of the Daitokuji Financial Group, focused on heavy machinery and military hardware. A billionaire industrialist, he initially pursued advanced alien technology for conquest after the Alpha Cygnan ship crashed on Earth. He manipulated the Japanese military into believing the stranded aliens were dangerous, orchestrating attacks to seize their tech. This involved deploying experimental mecha, some stolen from his daughter's designs like the Queen Margarita. During a confrontation where he piloted a version of B-ko's powered battle suit, he suffered a severe back injury that temporarily incapacitated him, though he later recovered.

His relationship with B-ko mixes mutual affection with frequent conflict due to opposing goals. They share cultural references like quoting Japanese poetry during fights, yet their clashes escalate to lethal force, compelling Hikari to respond with equal intensity to survive her attacks. He harbors an admiration for Elvis Presley, adopting Las Vegas-style jumpsuits for combat.

Over time, Hikari shifts from world-domination ambitions toward more conventional activities. By the events of Project A-ko 4: Final, he engages in matchmaking, specifically arranging a marriage between Miss Ayumi and Kei Yūki. This action directly instigates the central conflict when A-ko and B-ko disrupt the wedding. His narrative presence includes minor appearances, such as a scene near the story's conclusion alongside Kei's mother.