After Link has been sent to the Dark World, he encounters a maze outside the Palace of Darkness. While Link navigates the maze, Kiki the monkey begins following him. The monkey tells Link that he can help him enter the palace, but to do so, he requires a payment of Rupees. When Link discovers that the gate to the Palace is closed, Kiki offers to push a switch that opens the door, which is located on top of the temple, for a fee of 100 Rupees. Link obliges and enters the Palace. If Link refuses to pay the monkey either time, or if Link takes damage while being followed, Kiki leaves, and Link must repeat the process of encountering Kiki and paying him the fee of 10 Rupees. Kiki is not seen in-game again, although he does appear in the ending credits.
Kiki can be found outside Kanalet Castle, where he requires some Bananas. After he is given the Bananas, he will call his brethren and build a bridge to the castle as a reward. After they are done, they leave a stick for Link, which is used in the trading sequence in order to get the Magnifying Lens.
If Link approaches Kiki while accompanied by Bow-Wow, the two will instigate a fight, which will continue until Link leaves the area. This makes it impossible for Link to continue his quest without returning Bow-Wow to his owner, Madam MeowMeow.