Bat cash
This is pretty simple. In chapter 6 once you get under the monastery. There's cave that has a very large number of bats in. Now the first time you are in the cave there these wierd red flying mutants. But after you beat the skeletal dragon. you'll see him in a frozen state. Anyways after you beat him. That cave becomes full of bats. Have your normal shuriken equiped. Kill two bats with the shuriken. And then press and hold the Y button to asorb the two yellow essence into ryu sword. After you have asorbed the two essence into ryu's sword release the Y button to deliver ryu's ultimate attack. This results into each bat leaving a huge yellow essence gather them. Leave the cave then enter the cave again. Then this trick all again. Keep repeating this trick for about an hour and your will reach the max cash ryu can carry witch is 99,999.