This can be done on any difficulty setting. Session is basically a chapter. The game does not count Chapter 1 specifically as a chapter for this achievement. Therefore, the achievement can be gained from Chapter 4: No Way Out and onwards. You will probably get this without trying. A fairly quick and easy level is chapter 5: Pro and Anti-Venom. You do have to fight Anti-Venom, but it's not that difficult if you use your a lot. Just spam attacks (air strikes if you can). Anti-Venom is not defeated here, so do not think you have to take away all of his life.
Do not try to replay levels to get this achievement until you have beaten the game. It's actually quite hard to die in this game if you keep up with your attacks. Grabbing orbs gives you life as well. If you find yourself dying in every level, try replaying a level on easy difficulty.