Fallen Leaf: Part 20: Stage 1-15: Primian Ninja's Hideout
Those apemen enemies that are scattered throughout this World are called Primian Ninjas. They have a hideout that's just chockful of them.
Some of them are more showoff-y by striking a pose before attacking you with a divekick, and then posing again when they land.
The huge miniboss enemies are called Chukos. If you know about Mega Man 2's Wood Man stage, then fighting them will feel pretty familiar.
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The Gold Chest Treasure of this level is...
...a fat wizard named Corey. Or at least that's what he's dressed up as.
He claims to be Willow's #1 biggest fan... by showing how much of a creep he was towards him as to why he was sealed in that Gold Chest in the first place.
I don't think the young twins picked up on those implications, though, but also it's probably for the best of their innocence, too...