Instructions
 
Go to the garage near your starting point on the Estate Grounds to locate the Will-O'-The-Wisp. It is a greenish-colored floating light. 
Press the "L1" button on your controller to switch to your sprite-catching net. 
Approach the Will-O'-The-Wisp and swing the net by pressing the "X" button. If you net the Will-O'-The-Wisp, your sprite field guide will open, launching the sprite painting mini-game. 
Move the paintbrush with the left analog stick and press the "X" button to paint on the page. A picture of the Will-O'-The-Wisp will begin to appear. 
Complete the painting of the sprite on the page before the timer runs out. Once you finish the painting, you will capture the Will-O'-The-Wisp.