Name: Mitsuru Sano
Designation: Kamen Rider Imperer
Weapons: Antelope Visor, Horn Spear, Antelope Stab
Advent Cards: Gigazelle, Spin Vent, Final Vent
Contract Beast: Gigazelle
Although he came from an affluent family, Mitsuru Sano worked in a parking garage, occasionally cleaning rich people's cars. His father sent him out into the world so that he could learn the hardships of life and not be soiled by a rich upbringing. Because of his poor lifestyle, he believed friendship, respect, and love could be bought, and thus accepted Kanzaki's proposal to become a Kamen Rider in order to become rich and lead a happy life. He became a mercenary of sorts, attempting to sell his strength as a Kamen Rider to the various factions within the remaining Riders.

He first approached Shinji and Ren, lathering them with praise after seeing them fight. Though Shinji was fooled, Ren brought him back to his senses and refused him. Sano attempted to appeal to even Kitaoka/Zolda and Asakura/Ohja failing to gain employment from either. Sano finally turned to Satoru/Tiger and Hideyuki/Alternative for assistance. Kagawa, though knowing Sano did not fully understood his motives, allowed Sano to work with him and Satoru. After his father died, he inherited his father's business and became the boss of a major company. Because of his new found lifestyle, he wanted to give up the Rider war and enjoy his wealth.

However, Kanzaki reminded him of his contract with Gigazelle and its fellow Zelles as well as what would happen to Sano if he did not fulfill his side of the contract with them. Shaken, Sano decided to use part of his inheritance to buy the services of the other Riders, as he himself had tried to offer. Showing up at their doorstep with a suitcase of contract money, he appealed to Shinji and Ren, but was flatly refused. Sano tried the same tactics on Kitaoka, and seemingly succeeded, but Sano cancelled the contract days later after deeming Kitaoka "unreliable."

Sano's contract with Kagawa was later cut off when Kagawa was killed (by Satoru), but he still kept Satoru as a good friend and even hostelled him when Satoru was injured from battles before. It was then Satoru confessed his convictions and called Sano a friend. Though Satoru was grateful to Sano for caring for him, he later back-stabbed Sano, who was later wounded and left for dead. Though he survived the attempt on his life (which Satoru thought he did finish Sano off), Sano was ambushed by Ohja while attempting to make his escape back to the real world. Ohja destroyed Imperer's card deck with his Veno Crash attack, making him unable to leave the Mirror World and dissolve within minutes, screaming and begging for help.

In the 13 Riders special, Sano as Imperer was only seen at the final battle with Kamen Rider Tiger as tag team partners. In one ending, he and the remaining fighters used their Final Vents on Shinji. Imperer is unique among the other Riders because unlike the rest of them, his color scheme is inconsistent with his respective monster. Imperer doesn't have much fighting experience, using the Gazelle Visor on his right knee to use his Spin Vent card which gives him a double-drill Gazelle Stab guantlet. Aside from his Spin Vent, Imperer relies on his mass amount of Zelles to do the fighting for him, after which he lands the final blow. His Final Vent Drive Divider has the Zelles stampede a target before Imperer unleashes a powerful knee strike to the enemy's head.

Series:  Kamen Rider Ryuki