Bucky Stargate (バッキー Bakkī) is the robotic younger sibling to Jasmine and older sibling to Tetsuya and Luna. Originally built for destroying humanity, Bucky was later repurposed to protect Jasmine back when she was a child, however Bucky failed to do so because he was too soft because of his sister's teachings, so he sealed himself away until 2011. A year or two later he took a cat home and it turned out to be the gentle experiment of cruel people known as Luna. Tetsuya would later enter the castle after having found Luna, and Bucky had great animosity towards the Japanese-Canadian immigrant.
Bucky is voiced by Ryōtarō Okiayu via clips from Mega Man X5 and other games featuring the Zero character.