Nagumo went to Yugi's classroom during a break and asked to speak with Yugi. One of the classmates warned Yugi that Nagumo was good at games, but is also said to steal people's things. Yugi and Nagumo went to the roof and Yugi said that if Nagumo was looking to buy Monster Fighter stuff, his family's store was sold out. However Nagumo explained that he wasn't interested in buying any and challenged Yugi to a game of Monster Fighter and Yugi happily accepted.
After making a few moves, Nagumo admitted that Yugi wasn't bad, but pointed out that there was one house rule he always plays with; the winner takes the loser's monster and fighting gun. Yugi was horrified and didn't want to play under those conditions, but the game resumed.
Nagumo warned Yugi that he was wide open. Looking at "Alti", Yugi had no idea how Nagumo was concluding this. However Nagumo punched Yugi, knocking him down and proceeded to win knock "Alti" out of the ring, while Yugi out of action.
Nagumo kept Yugi's equipment as his prize. He said he had a lot of opponent's to face and next time they fight it will be more serious.
- Yu-Gi-Oh! Duel 43: "Monster Fight!! (Part 1)"