Find Charles! (サンタを探せ！, Santa o Sagase!, lit. Search for Santa!) is an event in Tomba!.
You can find the man who wants his hat in the background, blocking the door to the next area. Talk to him to activate the event.
Charles is located in a tree on the far end of Masakari Jungle. In order to interact with him, you must walk out on the bridge to the right and a short cutscene will play involving Charles rescuing Tomba from drowning when the bridge collapses. After a short dialog, Charles will return the hat. Go back and talk to the man to clear the event.