The Star Chip-theft victim was an unnamed character in the Yu-Gi-Oh! manga and anime.
He was a participant in the Duelist Kingdom tournament. However, on the first day of the tournament, his Star Chips and Deck were stolen by Mokuba Kaiba. Kemo grabbed the boy and tried to forcefully bring him to the boat transporting eliminated players from the island.
Yugi and his friends tried to bargain with Kemo, asking that he give them time to retrieve the boy's Star Chips. Although Yugi was successful in getting the Star Chips in the given time limit, Kemo didn't stay true to his word, and had already sent the boy away on the boat.
The boy made progress with his Deck during the first day's events, racking up at least two wins before being disqualified. After his belongings were stolen by Mokuba, his Star Chips were wagered in a Duel against Yugi, utilizing the boy's Deck. Yugi was quickly tipped off that the Deck was stolen, citing Mokuba's inexperience with the cards.
The only cards seen in his Deck were "Krokodilus" and "Man-Eating Plant".