Ninja Gaiden 4 contains 20 bosses. This guide shows all boss fights on Master Ninja, which is the hardest difficulty. You must beat the game on Master Ninja difficulty for the Way of the Master Ninja trophy & achievement.
Below are videos for all bosses sorted chronologically by chapter.
Chapter 1: D.D.O. Commander
Chapter 2: D.D.O. Proto-Goliath
Chapter 3: Kitsune Courtesan
Chapter 5: Sanzeon
Chapter 7: Kurobo
Chapter 9: Veilotl
Chapter 10: Cetus
Chapter 11: D-1018 Chario
Chapter 12: Elevator Fight D.D.O. Commander
Chapter 12: D.D.O. Proto-Goliath
Chapter 13: Kagachi
Chapter 13: Achilles
Chapter 14: Achilles
Chapter 15: Cetus
Chapter 16: Kitsune Courtesan
Chapter 17: Kurobo
Chapter 18: Totyos
Chapter 19: Ryu
Chapter 19: Dark Dragon
Chapter 19: Dark Dragon (Phantom Form)
More Ninja Gaiden 4 Guides:

MdMaynard says
Huge thanks for getting this out so fast, and for posting videos of the bossfights,I know posting videos in your guides mean more work though they the visuals are really helpful at times.
It looks like this one won’t be quite as difficult to platinum as its predecessors.
Thank you again for all your continued efforts on your guides. For me you’ve been a staple in the gaming community since my PS3.
David says
Hello! I have a question. The trophy says to beat all challenges, but there’s no mention of difficulty. Do we have to clear all challenges on every difficulty or just Master Ninja?