Folding Fan is the boss of zones D and F in Darius Gaiden. It is shaped after a fanfish.
Folding Fan's fight is mostly the same on the two zones he appear, with some of his attacks having it's properties changed depending on the zone. Both his opened mouth and tail are vulnerable. He will constantly move up and down while shooting four large bullets from his mouth. While moving, he will also constantly release triple spheres which break into three purple lasers when destroyed. After taking enough damage, he will move to the other side of the screen and unfold, firing lightning bolts to cover the screen. On zone D the bolts will shoot straight while on zone F they will curve. After this he will fold back and turn around, only to do the same lighting attack again. After this he will turn around again to face the player and shoot a cluster or bullets aimed at the player in an arc with a small gap on the middle, then resume his attacking pattern.