Sugoroku Mutou believed the hieroglyphics on the box read "The one who solves me shall gain the powers and knowledge of darkness." Yugi believed they said something along the lines of "Whoever solves this puzzle shall be granted one wish." and wished for friends. He brought the puzzle with him everywhere, usually keeping it inside the box, and spent eight years trying to solve it.
One day at school, Katsuya Jonouchi and Hiroto Honda overheard Yugi talking about the box. They took the box and teasing him over it, with Jonouchi taking a piece, without him noticing. Yugi got the box back when Anzu Mazaki intervened.
When Yugi solved the puzzle, he stopped storing it in the box and wore it around his neck.