The second time you encounter Master Kohga, he creates a Fanplane to attack you.

Defeat Fanplane Kohga

When Kohga is riding on his Fanplane, he can activate Flame Emitters on the bottom of the Wing and fly toward you to attack you with them.

Find the Spring in the area, hit it if it has already been sprung, then stand on it to be launched upward. Draw your bow to slow time, and hit Kohga.

After your first attack, Kohga's Wing can launch explosives at you, so do your best to run away from them.

After that, he raises a force field in the front of his Wing, and wooden boards on the side, so you will need to be above him in order to hit him.