Hard Mode is busted. On Normal, bosses can be challenging at times but overall quite doable and the Ruins 'bosses' are challenging, sometimes wiping me at times depending on what enemy the boss uses on that floor.. Switching to Hard mode means that you'll probably get wiped in a few turns due to bosses having high damaging aoes, multiple turns and high crit rates. If you don't believe me, next time you get to boss, swap to hard for the first attempt, get wiped, then switch back to Normal. It's ridiculous. Normal enemies are pretty fine and they can make you worry if you're not paying attention, but they felt fair enough in the first dungeon. After getting pounded by Hastur 5 times in a row though, I switched it back to normal and only looked back once, which was when I got to the Umeda miniboss and swapped back to hard just to see if it balanced out by this point.
It did not.