Are you trying to play a perfect game?
I save a lot too, but if a character 'dies' I just accept that and go on with the mission.
Also note, that sometimes a single item, like the right elemental weapon on a good character, or just a few more levels can make all the difference.
If you fail a mission now, it may be possible to do it by just postponing it a bit and do 2-3 other maps first.
Except for the very first few maps, I didn't find anything hard about hard mode. The most important thing is, that you can't really lose. In other games, if you choose hard mode, it often means that a single failure will put you at a disadvantage, which the A.I. will eventually use to destroy you (Sengoku Rance for example, or Civ
). So going into hard mode as a newbie there means you are doomed.
In Kamidori you can always just go somewhere else and powerlevel as much as you want.