When you complete the Master Ninja round, it restarts again on the Master Ninja difficulty. Each round difficulty is represented by specific scores from the NG2 soundtrack.
Warrior: "Thundering Peril"
Mentor: "Foul Power"
Master Ninja: "Twisted Shadows"
Apon completing each round, you are rewarded with one Grain. Supplies are limited to: 30 arrows, 30 incendiary shurikens and one Ninpo slot. You have the use of the Windmill Shuriken, which is unlimited.
As i get each one done, i will upload them to my Youtube channel and then link them here. I still have to do Kusari-Gama, Vigoorian Flails, Tonfa and Lunar. I'll keep this updated as i progress.