Spoilers ahead for all endings.
In every ending that doesn't involve you, the MC turning against Sophie, Colette, and Cerise, the entire group takes days to find out what passages to use from the tome, and then turn into a bumbling, manipulated bunch of hacks at every turn...falling into traps, getting straight up intimidated into obeying Mira, or being turned against one another (frustratingly even when Colette, regardless of her feelings toward you, should have a much more emotional connection toward Sophie).
And then...on the Incubus route, suddenly Cerise's shy, stunned weakness is no more, they all found the correct binding, and banishing passages in LESS than one day of recovering the Tome, and despite the number of Demons being even greater in favor ( 2 demons vs 3 human girls), the entire Incubus route falls apart so easily at every step, no one seems remotely intimidated by neither Mira nor you, and everyone seems to be on their A-est of games, it almost feels tacked on. Not to mention, even if you get Sophie into Mira's lair to feed, she doesn't do jack to stun anyone else, but back on the main routes a starved Mira has no issue warping Sophies mind into a voeuristic fantasy, or Colette's mind into domination fantasy, and then immediately turn Cerise into a scared puppy to hand over the tome...
The implication could be that "Well clearly the MC is a fucking moron and is the reason everything falls apart" except in the mainline non-canon ending route...you have to be the one to remember the proper incantation, so clearly that implication doesn't track either.
This didn't ruin the game for me. Honestly this is all that stood out in the game but it was so glaring to me that it made me actually stop playing while hunting for endings because the sudden tonal shift from the mainline story groups "We are so underprepared and overpowered by one succubi" to the incubi route group being "We're totally prepared, and not even remotely intimidated by two sucubi/incubi".
It's especially silly considering all that needed to be done to stop YOU in your tracks was one two-word Latin phrase, but never once in the mainline story is this used on Mira.
Anyway, I'm sorry if this came of as negative. The story as a whole, the music, the voice acting and oh my god the art especially are so damn good, I shotgunned the entire thing in like, a day and a half because I couldn't get enough.