Kurogane knew there was no stopping the kid, there never would be. He just like the rest of these damn fools would do what they wished for the one's they loved. He understood, it was a noble thought. If he was sincere, and Kurogane doubted this kid could ever not be sincere, then he'd show his faith in his return. He'd stay. He would wait for Syaoran to return. However, there was going to be a time limit, Kurogane wasn't an idiot, the chances of the kid dying were high, in fact rational, normal human beings probably wouldn't have left him go off and fight. Kurogane did though, he understood. Kurogane was honest with the kid, after sunset he was acting on his own. Which begged the question. With half of their group dead what would be the reason for living? Revenge. After Syaoran gave it his all and…well anyway after that Kurogane would extract his long, painful, bloody revenge These people were under his protection, so decided by him, and as such their deaths would be avenged. . He'd make sure not to die though, someone needed to take care of the princess, and Syaoran would have a shit fit if she was left alone to fend for herself in an unfamiliar world.
Unwittingly Kurogane gained a new strength that night. The strength found in waiting, found in faith in those he trusted.