During a train journey with Iris and Cilan, Satoshi discovers an injured Keldeo on the roof. He intervenes when Kyurem attacks, forcing their retreat into a tunnel. Satoshi then helps transport Keldeo to Roshan City's Pokémon Center for treatment. Learning of Keldeo's defeat by Kyurem and the imprisonment of the Swords of Justice (Cobalion, Terrakion, Virizion), Satoshi agrees to help rescue them.

Satoshi joins a plan to distract Kyurem. Iris commandeers a zeppelin while Cilan lures Kyurem and Cryogonal using a Stunfisk-powered mine cart. Satoshi and Keldeo proceed on foot towards the Full Court mine where the Swords are trapped. Inside, Satoshi, aided by Pikachu, Pignite, and Boldore, attempts to free the frozen Swords of Justice. This draws Kyurem's aggression; Keldeo intercepts the attack, showing renewed courage.

In the climactic battle between Keldeo (Resolute Form) and Kyurem, an energy blast threatens Satoshi and his Pokémon. Keldeo deflects it using the newly learned Secret Sword, saving them but sustaining further injury. After Keldeo concedes to Kyurem and is accepted as the fourth Sword of Justice, Satoshi evacuates the collapsing mine alongside Keldeo and the freed Swords.

Satoshi functions primarily in a supportive capacity, facilitating Keldeo's journey by providing initial aid, participating in the rescue strategy, and unintentionally motivating Keldeo's pivotal act of heroism. The narrative focus remains on Keldeo's development and conflict with Kyurem.