In the One Year War, Slender joined Gene and Denim on a reconnaissance mission to Side 7 under the command of Char Aznable. While inside the colony, Slender remained near the exit to keep watch as Denim and Gene ventured deeper. Following Gene's sudden attack, Slender sent a report to Dren and Char and managed to escape after Amuro Ray boarded the RX-78-2 Gundam.
Later, Slender engaged in combat with the Gundam alongside Char as the White Base departed from Side 7. However, he was ultimately killed by a single shot from the Gundam's beam rifle.
