One night in November 2018, they were kidnapped, along with 16 other children, and were split up from each other. Nona was sent onto the Gigantic and Ennea was placed in Building Q in the Nevada Desert, because she was proficient at transmitting messages through the morphogenetic field. There, Gentarou Hongou tells the children that their brothers and sisters are on board the Gigantic, and if they don't help them escape from the ship, they will drown. Ennea, Clover and the rest of the children in Building Q transmitted the solutions to the escape rooms through the field and all of the children, except a girl named Akane, apparently escaped alive from the game. The children from Building Q were rescued by unknown means and were eventually reunited with their families.
When Ennea and her sister came back home to their mom, they refused to talk about what happened during the game, because of the trauma they went through, but they eventually got over it. Curious about their ordeal, Hazuki tries to investigate why they had disappeared, but finds nothing because Cradle Pharmaceutical and possibly Free the Soul covered up what really happened. Nine years after being kidnapped, Ennea's mother is kidnapped for the Second Nonary Game.
- "Ennea" means "nine" in Greek.
- "Nona" means "nine" in Latin.
- Ennea and Nona are the only known identical twins that participated in the First Nonary Game.
- Her name was revealed in the 999 Q&A session.
- Ennea is the only character besides Clover who has been revealed to have been in Building Q during the First Nonary Game.