Man, this series was always on thin ice with its cringey premise and predictable set of characters, but holy hell did this chapter ever dive headlong into full blown cliche shonen/chuuni nonsense garbage.
As was said above, the posing, the mystery power up out of nowhere, the switch-flipping evil (though I imagine we find out that at least the dickhead hero guy is being mind controlled by the prince. As for the future-sight one, you'd think that he would know the truth and naturally object, but I'm sure there's some crappy hand-wave to try and make the logic go away), the goofy evil villain demon things. All of it smacks of either desperation to improve the story's readership by throwing every possible cliche that's ever been popular at the wall or the author running out of ideas already and just reaching back into the bag of generic slop manga tendencies.