

Mamoru's alter-ego as Tuxedo Mask caught the love of Usagi Tsukino/Sailor Moon after she saw him for the first time. It was also starting from episode one that he comes to help Sailor Moon in battle as Tuxedo Mask. After meeting Usagi for the first time, he started calling her "Bunhead," a nickname he'd call her by every time they met, much to Usagi's annoyance. Mamoru first appeared in episode one of the series. Believing this Silver Crystal would help him restore his memories, Mamoru would adopt the persona "Tuxedo Mask" and seek out the crystal for himself. He did, however, constantly have dreams about a mysterious girl begging him to find something called the " Silver Crystal".

The incident gave Mamoru retrograde amnesia, leaving him unable to remember anything about his life prior to the car accident including his own name. His parents died leaving Mamoru as the sole survivor. Mamoru was an only child and had lived with his parents until the day of his sixth birthday when all three of them had were in a car accident. However, Mamoru also has a good nature and while his words may seem critical, there is good intent behind them: his ultimate purpose (similar to Rei) is typically to inspire the person to better themselves. He can also be blunt, which has led to him sometimes upsetting those around him due to his harsh words. Because of this, he seemed to be very cold-natured initially and lacked many friends. He has likely suffered from loneliness and depression his entire life, and has trauma from the death of his parents resulting in memory loss (until midway through the first season). Mamoru is very protective of those he cares about, risking his life to save them. Mamoru carries the red rose when he transforms into Tuxedo Mask as explained below and upon meeting with the Outer Senshi in Sailor Moon S, he quickly transforms into this form while being covered in dead leaves being floated in strong winds. In Episode 81 at the finale of Sailor Moon R where he shields Sailor Moon from Black Lady's attack, both his hat and his mask were knocked off to show his true identity. He also wields a black cane and the red rose that he throws on his enemies. He wears a white mask and a formal long hat. As Tuxedo Mask, Mamoru wears a formal black tuxedo suit with a black cape and a red interior.
