Use one of Seiko's to humiliate her

Ruruka knew that if Seiko trusted one thing in this world, it was the **** she created.

It was kind of creepy.

Ruruka waited until Seiko had to take a bathroom break from her research before she could sneak in to find what she wanted.

She looked at the shelves filled with the **** that Seiko had worked hard on.

Just from a glance, Ruruka could see some that would be instantly useful in her **** but which one would she pick?