He is a member of the Shachihoko Group. He is, supposedly, the weakest member of the group. He is usually with his friends Sha and Chi, amongst who Sha is the strongest. They are all from a local karate club. They like to collect cards by defeating any duelist they found passing by. They all use similar decks and strategy to defeat their opponents.
One day they found Benchan and stopped him and asked to duel them. Benchan told them that he does not duel but she had a hunch that he is having a collectable cards folder with him. Then Katta came looking for Benchan and saw him in a situation where he was out numbered. Katta pretended to be Benchan "the guy with glasses" and dueled Chi. During the duel, Haj clearly saw Katta being an amateur and asked Chi whether it is alright to defeat him like that and Chi responded that it is and that he will learn from this lesson. Chi then defeated Katta. Then Sha, the strongest of them, dueled Benchan, who wanted to avenge Katta, and he defeated Sha. Later the following day, they returned with their group boss, Onsen, who then defeated Benchan.