He answers the door, recognizing the voice. Kankuro must have found his cake by now. Chouji knows full well how predictable he is. Food left in the kitchen is often from Chouji, plus his handwriting might give it away. He didn't leave a note with his name, sure, but he also was hardly trying to remain anonymous.

Chouji smiles. "Happy birthday. Temari told me, otherwise I wouldn't have known it was today."