Marzio is the civilian name used in the Italian adaptation of Mamoru Chiba, the male lead of Sailor Moon SuperS. As a teenager, he lost his parents in a car accident on his sixth birthday, an event that also erased his early memories. He later learns that in a past life he was Prince Endymion, the guardian of Earth and lover of Princess Serenity, the moon princess who would be reborn as Usagi Tsukino. In the present, Marzio is a serious, caring, and sometimes sarcastic young man who feels a deep, instinctive need to protect Usagi and her friends. He transforms into the masked hero Milord, also known as Tuxedo Mask, whenever danger threatens them.

In Sailor Moon SuperS, Marzio continues to act as the Sailor Guardians' ally against the Dead Moon Circus, a group that seeks the Golden Dream Mirror and the power of Pegasus. His role is primarily supportive: he appears at critical moments to distract enemies by throwing roses, offer strategic advice, or provide emotional reassurance, especially to Usagi. He shares a strong romantic bond with Usagi, and their connection often allows him to sense when she is in peril. He also has a caring, protective relationship with Chibiusa, daughter of his future self and Usagi, who is a central figure in the season due to her dream meetings with Pegasus. While Marzio does not gain new powers in SuperS, he remains a steadfast presence whose psychic link to Usagi and his own combat instincts make him a valuable member of the team. His development in the season is subtle, as he continues to balance his everyday life with his duty as a masked protector, growing more confident in his role alongside the Sailor Guardians.