Mamoru Chiba, identified as Armando Chiba in select localizations, operates both as a civilian and the heroic Tuxedo Mask, playing significant roles throughout the Sailor Moon narrative. A tragic childhood car accident on his sixth birthday claimed his parents and induced retrograde amnesia, erasing memories predating the crash. This trauma sparked recurring dreams of an unidentified woman compelling him to find the Silver Crystal, unknowingly prompting his nocturnal transformations into Tuxedo Mask. Driven by the conviction that the Silver Crystal could restore his lost past, his quest frequently intersected with the Sailor Guardians' missions. In civilian guise, Mamoru Chiba presents as a high school or college student (depending on adaptation) with short black hair, blue eyes, and a reserved manner. His typical attire includes turtlenecks, jackets, or school uniforms. As Tuxedo Mask, he assumes a formal black tuxedo featuring golden buttons, a red-lined cape, a white mask, a top hat, and white gloves. He commonly wields a cane and employs roses as projectiles or symbolic gestures. His transformation initially activated involuntarily when sensing Usagi Tsukino (Sailor Moon) in peril, though he later gained conscious control. Mamoru wields abilities tied to his role as Guardian of Earth. These encompass psychic powers: psychometry (reading objects or people via touch), energy projection for defense or offense, healing capabilities, and premonitory dreams. He possesses the Golden Crystal, counterpart to the Sailor Guardians' Sailor Crystals, granting him guardianship over Earth and aligning with his name's meaning "Protector of Earth." His relationship with Usagi Tsukino (Sailor Moon) forms a core narrative thread. Initially antagonistic civilians—exchanging teasing nicknames like "Bunhead"—they forge a deep bond upon discovering their past lives as Prince Endymion of Earth and Princess Serenity of the Moon Kingdom. Their romance endures through multiple reincarnations and challenges, including temporary separations prompted by prophetic nightmares warning of global catastrophe should they stay together. These trials ultimately strengthen their destined connection, leading to marriage and a future daughter, Chibiusa, in the 30th century. Character development progresses across story arcs. Regaining memories as Prince Endymion during the Dark Kingdom conflict precedes his capture and brainwashing by antagonists, causing clashes with the Sailor Guardians before redemption. Subsequent arcs (Black Moon, Infinity) explore his protective instincts toward Chibiusa, struggles with destiny-imposed separation from Usagi, and evolution into a strategist and supporter alongside the Sailor Guardians. His emotional journey involves overcoming loneliness and trauma to embrace his duties as Earth's guardian. In non-core media, like the theatrical short *Make Up! Sailor Guardians*, Tuxedo Mask appears in his supportive battle role or narrative recaps, affirming his alliance with the Sailor Guardians. Stage musical adaptations introduce variations: backstories where Queen Beryl was his past fiancée or where Sailor Pluto confesses unrequited feelings for him. The live-action series further diverges, depicting his Tuxedo Mask persona as a deliberate disguise for thievery aimed at locating the Silver Crystal, and includes a plot where he becomes "Dark Endymion" after absorbing malevolent energy.