Functions and flaw
The Nep-Note can be used as a regular notebook to record notes. It can also be used to capture and store living beings of any size inside of it. If the being is particularly large, it will be shrunk to fit the notebook. The book has served as a prison for Croire and Arfoire. If the being is inside the Nep-Note, the user can use the captured being's ability.
One particular being's ability is Croire's dimension traveling capabilities. She can normally only do this for herself. While inside the notebook, Neptune has used the book to travel between dimensions. Additionally, the book can be used to create portals to allow anyone number of people the ability to travel between dimensions.
Its flaw, however is that anyone with enough strength can bust out the prison.