To get the bellybutton ring of eath you just search around in the treasure place in alumaru village and you will fall down holes and you get the treasure in the basement of that place and one item is the belly button ring of earth

To be perfectly honest with you the rings are not as much help as they sound. as you continue to play through the game i found a lot of better gear. I will try not using them and tell you all how i do. and btw i will be making a guide showing everyone how to play the game professionally. i have read a lot of the forms about this game but it seems that i was able to kill almost all the boss's at lvl 20-30. i killed moody dragon at lvl 22 (all characters). The game is mostly based on your shadows. If you are going after all the achievements like I am (first time play through) then sorry to say but you have to level your characters... but otherwise killing them is a easy at low levels.

actually the easiest way to kill all the dragons except phantom dragon is to equip life crusher bracelet to shu and do normal attacks.