Acclimation is pretty much the hell points you get from defeating monsters and walking into those green circle light thing. The more hell points while in the pandemonium dungeon, the more gold and experience u get in battle. The amount of hell point you have is shown in the bottle left corner of the game screen, the max you can have is 50 (65 with an skill upgrade in 3F town or 75 with a specific tomb equipment) Whenever you leave pandemonium, those hell points is reset back to 0 and depend on how much you got, you will also get a special reward (20 for heal herbs, 30 for potion, 50 or archdeamon crystals, anything over 50 will be converted into magic materials used for pronant). All the hell points you got is acclimated, you can use them in your inn at a light point thing right before the door to pandemonium, which can be used to strengthen you or your girl's skill.