Nagi Shimamoto is a worker at the Futo Bird Sanctuary who becomes the unwilling subject of Shinkuro Isaka's experimentation with the powers of the Quetzalcoatlus Dopant. After he kills her father, she is made to be the Quetzalcoatlus Memory's user and both her compatibility with the Memory and her fear of Isaka makes it stronger for him to use later. Isaka makes a copy of the Quetzalcoatlus Memory and uses it on a Red-and-green Macaw to further frighten Nagi by showing a sample of the Memory's powers as the giant Quetzalcoatlus Dopant, the monster Isaka would have her become. The Dopant drags Nagi off until Kamen Rider Double saves her. The copied Dopant is defeated by CycloneJoker Xtreme's Bicker Charge Break. Kamen Rider Accel Trial later destroys the Quetzalcoatlus Memory before it can be used on Nagi to make it more powerful for Isaka's use.
- Nagi shares some similarities to Nodoka Miyazaki from Mahou Sensei: Negima!!:
- Both were portrayed by Miyuu Wagawa.
- Both started their character as the scared and shy type of character which gradually changed because of the encouragement of their respective heroes.