The fifth tribute (title)

Earth is still ignorant as far as interstellar wars go. When earth is about to be annihilated the rulers of countries can negotiate with the species about to raid them. Earth has to keep the existence of their overall rulers a secret, have to stay in contact with them constantly, have to accept the observers from the occupying race and have to send them four tributes for four of the five Princes. When the tributes were chosen and got beamed up, surprisingly, a fifth tribute was beneath them. How will their story unfold?

Something along those lines for the starting point. These are the tributes. With one unwanted one. I suppose Anne and Rei-chan act the most appropriate considering they´ve been sent somewhere unfamiliar. Still, I like the attitude of the other three more.

Anne: "We... we shouldn´t just roam around. Don´t you know? Curiosity killed the cat!"
Robin: "Fortunately, we´re not cats."
Rei: "Koko wa doko desuka."
Suzume: "Shiranai. Ikoze!"
Henriette: "...?"

Robin is the only one able to talk with everyone considering he´s fluent in many languages.