| Katsumaru |
|Voice Actor|| 嶋村侑 |
He is Katsuzo Kirifuda's pet dog.
Katta once asked him to find Benchan by showing him a photo of him but he instead took Katta and showed him an artwork of a similar looking person. He later went along with Katta to Ken's house where Katta and his friends trained their dueling skills.
During the time Onsen escapes the hospital and obtained Prin Prin, the Eternal, he along with Hako and Monjiro followed Onsen's teammates secretly and also helps her in blocking the path of the tournament staff to buy Katta time for his final duel against Onsen,