@givemersspls They didn't mean it literally that they are immortal without the sword. "That knowledge alone is not enough for a human to slay us" Just meant that knowing the sword will give them an advantage still won't surmount the gap between their actual abilities.
@givemersspls I think the demon lord meant to say that humans are weak,and it'd take more than a weapon that's super effective against demon lords to kill her.
They clearly choose demon lords based on how nice your horns are. Negating what makes her the demon lord actually means it can cut her magnificent horns!
I think the demon queen won't join any harem. As for the demon girl, I still think she'll get w/ the MC, because it seems they've set up a lot of tension with his hatred of demons just so that could be overcome.
Kail has been shown to use demon blasts during the tournament and that suspicious black winged demon lord motif when he killed the king after saving the princess during the hydra incident.
It's almost guaranteed that Kail is either a Demon (unlikely). . . . or he brought over the Black Winged Demonlord or some Demon's soul from the last time period.
Remember, Kail has two souls, but who said it had to be two copies of Kail's soul? Why can't one be from the Black Winged Demonlord. Or some other Demon's