I'm one of those idiots that has to play everything on the hardest difficulty, so when I stumbled upon this game and actually enjoyed the artstyle, and the unique combat elements present in the tutorial, I became hooked, and immediately got to work on figuring out hard mode, but ultimately it's just a bit overtuned.
While it's relatively simple enough to grind aura stats with reading and equipment bonuses etc, this isn't really an option available to your allies, who usually die in 1-2 hits at absolute maximum while also being out-sped. The game is overly reliant on *excessively* good RNG and/or removing your collar against bosses which equally trivializes everything - and that's assuming you've even navigated dungeons perfectly, avoiding all encounters to keep them fresh, which is itself inconsistent with the speed and erratic movements of some enemies.
Please don't misunderstand though, these are all interesting mechanics that make the game unique among any RPG, I just think the balance is off. The highly variable RNG in hard mode feels contradictory to what actually made me like the game in the intro. Critical hits and dodges happen because you hit enemy weaknesses, pre-emptive strikes and ambushes occur because of back attacks in either direction. Conserving your resources for mandatory fights since normal fights don't offer much is consistent when enemies follow set and readable patterns of manageable speed.
I think the best hard modes in games offer some tangible benefit to playing it to make it more interesting than just misery. As it stands, beyond clear room ng+ points (Tales grade??) everything has downsides. Doubled costs, 'lengthier' books, doubled curses, all on top of 30% enemy buffs that feel much higher than 30% because of how calculations work. Example using basic goblin stats. There's some variance, but obviously 40-34 is 6 damage, however on hard mode it's 52-34=18, where again there's some variance. 3 attack points and their damage triples.
This is a bit long, but you genuinely have some great ideas on both the RPG side and the lewd side. Just bring hard mode down a bit man.