Oh YES! a hard JRPG :D I'm in love! whats it like on normal?
You should ask that to Rol, I think he's already finished/almost finishing the game on Normal. I only know that, for example, the chapter 3 end boss on Normal has about 50000 HP and has about 200 P.Atk. On Hard he has 95000 HP, 380 P.Atk and almost double in every other stat. Even against a level 50 party, most of his attacks are OHKO if your characters aren't defending.
I've currently hit Chapter 4 and there are regular mobs that can wipe out the party before you can act (if they get a pre-emptive strike on you then it's an instant game over 99% of the time).
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"