First you want to pass the tutorial and i recommend beating the game but you don't have too. Next you buy some moderate gear then you hit restart rebirth 1. Make sure you don't hit reset character. Then you click the arrows by the infinity blade, you want to have at least 50,000 dollars. Next you beat Saydhi and hit inventory and equip your sword and sell the infinity blade don't worry you will still be able to put the infinity blade in the slot and keep repeating this. Also if you just started try to save enough money to unequipe the water gem and then if you just started your going to need approximately 130,000 dollars to unequipe the gem. (Also you might keep the armor, shield, and helmet but you might not and to do that you only sell the infinity blade.) Hope you guys enjoyed the tip.
Make a point of checking the same places for hidden items during every playthrough.
How to keep a water gem without loosing it after tutorial?
the +100 water attack gem which is given to you in the beginning of tutorial. Put the gem into your inventory as soon as you get the gem. Otherwise you will loss it after you finish the tutorial, then go straight to rebirth.