Instructions
Befriend the old man Kannon. Speak to him while he's inside the tower, and whenever he asks you to hand him an item or bring him something, do so. Once you have befriended him, Kannon will mention that his granddaughters are moving in -- Candy and Cinnamon.
Go to the lake to look for Cinnamon. On days when it isn't raining, she will be fishing. Talk to Cinnamon.
Follow through the conversation and Cinnamon will give you a fishing pole at the end of it.