Noire arrives in Planeptune to visit Neptune for her break. She heads to the Basilicom and sees no one around. Noire decides to kick back and wait for them to return before hearing Neptune and Nepgear's voice. She realizes that was she was sitting on was in fact and extremely giant and incredibly fat Neptune.
When Noire asks how she got that way, Neptune tells the story of how she went out on a quest and realized she forgot her lunch which resulted in her eating a mushroom. Histoire, who is stuck inside Neptune's fat, tells Noire that this is the result of the Just Get Fat" mushroom and that in order to cure Neptune she must go out and find the "Just Shrink" mushroom before it's too late.
Noire head out and quickly gets the required mushroom, but as she returns to Planeptune she sees that Vert and Blanc are also there. They explain that they arrived due to having received word that a giant monster had appeared in Planeptune. Together, they all work to get the mushroom into the giant Neptune's mouth and shrink her back to normal size. After this event, Neptune ends up eating another "Just Shrink" mushroom and ends up getting smaller.
- Noire visits Planeptune and sees no one is around in the Basilicom.
- Noire sees that Neptune has gotten extremely fat and is sent off to get a "Just Shrink" mushroom by Histoire to cure her.
- Noire arrives back in Planeptune only to see Blanc and Vert there as well which results in them working together to feed Neptune the mushroom.
- Neptune goes back to normal but ends up eating another "Just Shrink" mushroom and getting smaller.