Wonder Boy in Monster Land/Round 5

When you proceed into the set of trees, jump at the third one to find a bag of gold. Proceed onward until you see what appears to be a well.

When you fall down, head to the right. One of the raised platforms has its green markings a bit further to the left than normal (specifically, the third raised platform to your right). Search for a secret door to fight a giant rock thrower. After you defeat him, you collect an improved sword and can continue to the right.

Pass through the fillage, and walk along the ground. You should fall into an invisible pit, where you can collect a key and fight four bats. As you defeat them, platforms appear allowing you to leave at the top. Proceed to the right to finish the round.