Draw Slasher

Story related, cannot be missed.

Phantom is the boss at the end of Chapter 5. This is one of the easier boss battles. Phantom releases tiny monkeys which attack. They are quite easy to kill, simply slash side to side very close to the ground. He releases the monkeys in waves, and once you kill them all you can slash him once to deal damage. Each time you hit him he will release a new wave of monkeys, and as the battle progresses there will be more monkeys per wave. The technique to defeat them never changes, and you can probably clear this boss taking little to no damage.

Completing Chapter 5 will also unlock the next 3 Challenges (12-14).