Mamoru Chiba is the reincarnation of the Prince of the Earth, and transforms into Tuxedo Mask (known as Tuxedo Kamen in Japan). However, Mamoru did not realize that he had transformed into Tuxedo Mask whenever the Sailor Senshi were in danger. He attends college at the Azabu Institute of Technology during the day, but can appear as Tuxedo Mask to help the Senshi at any time of the day or night. Shortly after his Tuxedo Mask identity is revealed to the Sailor Senshi. Mamoru helps Usagi and the rest of the Senshi during their time of need when things start going out of control when Galaxia transports them to Domino City. He attends Domino University with Michiru, Haruka, and Setsuna.