Yoko Ishigami serves as a leading research professor at the SuperLife Center, focusing on genetic engineering. Her demanding career created distance from her son, Ryosuke Ishigami, straining their relationship. Driven by a conviction that genetic manipulation could enhance any lifeform, she pioneered experiments fusing human and animal DNA. This research yielded Bagi—a hybrid being with mountain lion and human traits—designed to explore biological enhancement limits. After an outbreak decimated the facility, Bagi and her mother survived, though Bagi’s mother was later hunted, leaving Bagi solitary until meeting Ryosuke.

Yoko shifted her work to South America’s Cucaracha Research Lab. Under presidential orders, she engineered a strain of rice later revealed to carry a lethal poison for weaponizing against dissidents. Consumed by guilt over her work’s misuse and acknowledging ethical failures as both scientist and parent, she allied with Bagi to destroy the rice. During their mission, Yoko drew the attack dogs of the president toward herself, sacrificing her life so Bagi could eliminate the project. She left a final letter for Ryosuke, confessing profound remorse for neglecting family and enabling destruction. Ryosuke discovered this letter after mistakenly assaulting Bagi, learning his mother’s regrets and motivations.