Mamoru Chiba, the young man who transforms into Tuxedo Mask, is introduced in the live-action series Pretty Guardian Sailor Moon with a backstory that sets him apart from other adaptations. In Act Zero, which functions as a prequel, Mamoru is already consciously aware of his dual identity as Tuxedo Mask, a significant departure from versions where he is initially unaware. His origin is touched upon in one of the mini-dramas included with Act Zero: as a child, after scraping his knee, Mamoru encounters a mysterious older man dressed as Tuxedo Mask who uses some form of healing magic to mend the wound. This encounter leaves a lasting impression, and he later recounts the anecdote to Usagi Tsukino, hinting at an early, fateful connection to his masked persona. In terms of personality, Mamoru in this live-action adaptation is depicted as a more silent and reserved individual compared to his animated counterparts. He is deeply dedicated and carries a strong sense of duty, which is reflected in his motivations. He initially seeks the Silver Crystal to recover his lost memories, driven by fragmented dreams. His role in the story is that of a mysterious ally who operates from the shadows, aiding the Sailor Guardians. A notable aspect of the Act Zero content is that Mamoru uses a transformation phrase, Tuxedo Power, to become Tuxedo Mask, a detail that is specific to this production. His abilities during this period are largely physical; his primary weapon is a cane, and he does not throw roses as he does in the anime. His costume, which he wears to conceal his identity, is sometimes repaired by his friend Motoki Furuhata, who believes the outfit is for a part-time job. Key relationships are established early: his romantic connection with Usagi Tsukino begins to form, though she is unaware of his secret identity, and he is also bound by a childhood promise to a girl named Hina Kusaka, whom he is engaged to, creating a complex emotional dynamic. Over the course of the series, his development involves gradually reclaiming his memories and fully embracing his destiny, moving from a solitary figure searching for answers to a dedicated protector fighting alongside the Sailor Guardians.