Shotaro Hidari is the left half side of Kamen Rider Double. He is a self-dubbed "hardboiled detective", though considered "half-boiled" by others, who dresses in the style from the 1970s. He works as a detective in the city of Futo under his mentor Sokichi Narumi.
Vowing to ensure that no one ever feels sad, Shotaro took on the job as the protege of Futo's private investigator Sokichi Narumi. However, in the investigation into a mysterious organization that led to Shotaro meeting Philippe, Sokichi is shot to death, leaving Shotaro to continue in his stead. Refusing to let his mentor's death be in vain, Shotaro works to stop the Dopant crime wave by being the man on the street, contacting his various informants and transforming into Kamen Rider Double by providing his body for the formation.
His surname is literally translated as "left" (左, hidari) and his Gaia Memories provide the left side of any Double formation.
Gaia Memories
The Gaia Memories (ガイアメモリ, Gaia Memori) are mysterious USB flash drives imbued with the powers of the Earth itself. Originally created with funding by the Sonozaki Family, these Gaia Memories end up in the possession of Shotaro and Philippe, and can only be used through the Double Driver. Two can be inserted into the Double Driver, allowing Shotaro and Philippe to transform into Kamen Rider Double. Shotaro's left-half Memories called Body Memories (ボディメモリ, Bodi Memori) determine the type of attack or weaponry that Double uses.
- Joker Memory (ジョーカーメモリ, Jōkā Memori): The Joker Memory, also known as the Trump Card Memory (切札の記憶, Kirifuda no Kioku), allows the user to increase fighting potential, becoming the Skill Warrior (技戦士, Waza Senshi). When used, half of Kamen Rider Double becomes the black Trumping Left Half (切り札の左半身, Kirifuda no Hidari Hanshin).[1][2][3] When the Joker Memory is placed in the Maximum Slot on the Double Driver, it allows Double to execute the Joker Extreme Rider Kick.
- Metal Memory (メタルメモリ, Metaru Memori): The Metal Memory, also known as the Steel Memory (鋼鉄の記憶, Kōtetsu no Kioku) or the Fighter Memory (闘士の記憶, Tōshi no Kioku), empowers the user with great strength, becoming the Superpowered Warrior (怪力戦士, Kairiki Senshi). When used, half of Kamen Rider Double becomes the silver Fighting Left Half (闘士の左半身, Tōshi no Hidari Hanshin).
- Trigger Memory (トリガーメモリ, Torigā Memori): The Trigger Memory, also known as the Sniper Memory (銃撃手の記憶, Sogekishu no Kioku), turns the user into an expert marksman, becoming the Gun Warrior (銃戦士, Jū Senshi). When used, half of Kamen Rider Double becomes the blue Sniping Left Half (狙撃手の左半身, Sogekishu no Hidari Hanshin).