To Max Out Health, complete the game one time using hard mode. Now start a new game and during gameplay press L1, L2, R1, R2, Circle Square, Square, Triangle, Circle
To unlock new ending, find all Kodama which you will need and increase all 7 Haori of Ako to maximum
Hard Difficulty: complete the game using normal difficulty
Easy Difficulty: lose the game 2 times using the normal difficulty setting
Issen Difficulty: complete the game using the hard difficulty setting
Oni Hard Difficulty: complete the game using the Issen difficulty setting