You're going to need to be more specific, but if you're talking about the chick on the last page:
She's a succubus, and is advisor/aide to the soon-to-be-new Demon King in the same way catgirl is to the current one, except way more incompetent. Her and new DK go through dumbass hijinks in the same way as Blonde Hero and his chick.
Didn't the demon king just say that they have to deal with an invincible godlike being before invading?
Wait scrap that, he just dominated a god.
How the hell is she so stupid?
@Strowy fuck yeah. It might take a while for me to see it because i don't read LN "weak eyes" but hey if their stupidity got the MC mad and make him fuck their entire shit up. Im in
wow that thicc but dumbass demoness with glasses on last page is hella suitable for a hentai/doujin character, if anyone knows pls link me. i got a request from my neighbour's cat's long distance relative with a quarter royalty blood cat family that demands research material for this specific thicc but dumbass demoness with glasses, such coincidence, much wow. research, academic n healthy living purposes of course
Well that princess did send MC to die and she expects that he will become hero? That is quite stupid, no matter how you look at it.
But MC will blindly help them, this is generic isekai manga.
@Pleaseletmehaveaname He doesn't mean deal as in kill, he's not that dumb. They need to figure out where Fulio is living now so they don't accidentally send the army in his direction. They're trying to finish the invasion without pissing the MC off.
So to those thinking this is final arc no there is a few more and slice of life style one after this. (Going off of novel btw) the DK’s brother is a dumb ass stereo type for demons. And yes prepare for lots of useless former hero shit. I want him to die so bad in the novel. He takes away from the main characters too much. This post has no major story spoilers just generic ones.