Planet Romanus is a planet in the "Zel galaxy", visited by Amy Rose and Tekno the Canary during their adventures with the Eternity Ring. Styled like Ancient Rome, Earth, one particular city is encapsulated within a giant energy dome. Inside, Emperor Zero rules over a select group of slaves, pitting them against each other in gladiator-style battles.
Amy and Tekno arrived on this planet and were immediately captured by Zero's hunt squad. After having to fight each other to the death, Amy was able to fight her way to the control room and disable the city's energy shield, allowing the planet's law enforcers to swoop in, arrest Zero and return the slaves back to society.