In episode 152, this card appears in a flashback that Mai Valentine has which relates to her many victories but feeling no joy from it. Mai uses this card during her Duel against an unknown opponent. When "Tri-Horned Dragon" attacks "Cyber Harpie Lady", Mai activates "Mirror Wall" to cut the ATK of "Tri-Horned Dragon" in half. The opponent then activates "Rush Recklessly" to raise the ATK of "Tri-Horned Dragon" by 700, but Mai activates this card to switch the target of "Rush Recklessly" to "Cyber Harpie Lady" instead, raising its ATK by 700. "Cyber Harpie Lady" then destroys "Tri-Horned Dragon", winning Mai the duel.
In this duel, either "Thousand Knives" or "Fairy's Hand Mirror" was unfaithful to its TCG/OCGeffect. "Thousand Knives" is only capable of targeting a monster on the opposing side of the field while "Fairy's Hand Mirror" is only capable of switching to a valid target. Therefore, "Thousand Knives" should not have been able to destroy Yugi's own "Dark Magician Girl".