"We're going back to the iron demon city!" Noa told the truth to motivate Buck again.
She could've used the slave contract to force Buck to move, but she knew once a demon accepted its death, it would not move by anything, even if you torture them to no end.
This was the inherited trait of demons!
Even the most cowardly ones can become extremely fearless once they accept death, and that's why it was almost impossible for other races to enslave demons because they'll submit to no other race!
Even Noa only submit to Ace because he had the support of a 'God'!
"Going back?!"
Just as Noa expected, Buck's listless eyes instantly lit up as his will to live aroused again. Because in Buck's mind, once they enter the Iron Demon City, anyone would easily recognize him because of his tribe's traits.