seems like these guys are in a cycle of posessing the title of Hero as a sorta weapon against the Demon Lord, but I'm guessing they either just straight up die or something bad happens to them once they do since their purpose was fufilled and they have way too much power to stay alive.
Why did protag get so weirdly determined after being explained this though shouldnt he be sad or at the very least melachonic? I mean you could see him visibly sweating while basically saying "fuck it we ball" so hes probably scared shitless but pushing through anyway; what an admirable protaganist