Rush is Mega Man's robotic canine companion, built by Dr. Light to assist on missions. He accompanies Mega Man when characters enter the real-world setting of Japan. In the first episode, Rush speaks directly to Mega Man and human allies like Yuuta Kobayashi. His primary function is transforming into a jet, providing aerial transportation for Mega Man and Yuuta as they pursue Dr. Wily across Japan, enabling rapid movement during investigations.

Rush actively confronts antagonists created by Dr. Wily. He battles entities such as the fire-based Magma Men, powered by Mount Fuji's volcanic energy, and helps defeat larger mechanized threats like the combined Samurai Man robot, offering tactical support. After the initial episode, Rush stops speaking but maintains his physical presence. He continues providing support during cultural explorations and conflicts, including participation in Obon festival activities without dialogue. During the confrontation with the Typhoon Robot in the third episode, Rush fulfills his assistance role without vocal interaction.

His background as Dr. Light's creation aligns with his established portrayal, though specific developmental history within the anime remains unexplored. Rush adapts to real-world environments without mechanical modifications or functional expansions beyond his predefined capabilities.