Shotaro Hidari

"Kamen Riders are this city's symbol of hope!"

- Shotaro, rejecting Eternal's claims to be a Kamen Rider

Shotaro Hidari (左 翔太郎) is the left hand side of Kamen Rider Double, but also a Rider in his own right as Kamen Rider Joker. A self-proclaimed "hardboiled detective", he dresses in a retro fashion based on late-1930s style, favoring fedora hats and waistcoats. He is often called 'half-boiled' by his friends, however, because he cannot fully shut out his doubts, often acts according to his feelings, and has difficulties making cruel yet necessary decisions, contrary to his hard-boiled aspirations. He works as a private detective in the city of Futo.

History
Vowing to stop anyone that makes his city cry after, as a child, witnessing Sokichi Narumi's first fight with the Spider Dopant, Shotaro eventually became Sokichi's protégé. His final job with Sokichi involved investigating a mysterious organization, at the behest of an equally mysterious client. While infiltrating a Gaia Memory research building, Shotaro met Philip for the first time. However, due to Shotaro's recklessness, their cover was blown and it indirectly led to Sokichi being shot to death. Sokichi then left Shotaro to continue on in his stead, giving Shotaro his prized fedora in his final moments. Shortly afterwards, Philip and Shotaro used the Double Driver - which Sokichi had been carrying, perhaps with the intent that he become the body of W - to transform for the first time, in order to escape.

Refusing to let his mentor's memory be in vain, and to atone for his mistake, 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 combination.

Shotaro's physiology is not ideal for Gaia Memory use, and he was never Shroud's ideal choice for the 'body' half of W. Because of this, he had trouble maintaining their Rider form when Philip's power was evolving. However, he later proves that he has a knack for being the 'wild card', being incredibly difficult to predict in such a manner - this quality leads not only to him resonating strongly with the Joker Memory and match Philip's heightened power, but also displaying the ability to exceed expectations and being able to transform into Kamen Rider Double CycloneJokerXtreme by sheer willpower.

Shotaro also appears to be the one who came up with the names of Double's finishers, as demonstrated in episode 16 when he decided to call FangJoker's Maximum Drive "Fang Streiser". Though this is ostensibly to enable him and Philip to synchronize themselves better, it seems Shotaro simply likes doing it, as he names his attacks when he fights solo as well.

Kamen Rider Taisen
Shotaro returns in Kamen Rider Taisen, as both Kamen Rider Double and Kamen Rider Joker. After being informed what happened in Japan, Shotaro meet with Tsukasa and Kaito, to be asked for finding someone related to Shun Aoi but refuse it due receiving job to search a dog, cat, and turtle (which Kaito claims so stupid). After being helped by Kaito, Tsukasa tells about the Heisei and Showa Riders are beginning to fight and he wants Shotaro to learn the reason as it is related to Shun. Soon, he confronts by two BLACKs who think that Heisei Riders are nuisances as they attack Tsukasa when he is taking Shun to his mother. Shotaro tells Tsukasa to leave it to him as he hold off the two BLACKs as Kamen Rider Joker. Katio soon helps him as Kamen Rider Baron. In the battle, with the Kaito's help, he defeats Black RX with Rider Kick.

At the climax, Joker is one of the surviving Riders in the battle between Heisei and Showa. He faces Kamen Rider Black, with the two Riders taking each other out with their Rider Kicks. Gaim is soon left as the last Rider standing before Ambassador Darkness of the Badan Empire reveals himself to be Ryo Murasame (Kamen Rider ZX). He, alongside all 30 Kamen Riders are restored to defeat the Badan Empire.

In the conclusion battle, he fights Niigo and stopped after Ichigo proclaims his lost against Gaim.

Kamen Rider Travelers Record
Aside from Kamen Rider Double, Shotaro appears transforming into Kamen Rider Joker in the video game Kamen Rider Travelers Record.

Personality
Shotaro's basic personality is an homage to the fictional detective Philip Marlowe (ironically, his partner's namesake), as is his aspiration to be a hard-boiled detective. Shotaro's decisiveness and honed detective intuition make him a remarkable detective even without the help of his partner. However, his friends and contacts often refer to him as 'half-boiled', as he wears his heart on his sleeve and let his emotions get in the way of making the cruel yet necessary decisions that real hard-boiled detectives, such as his mentor, would have little problem making. Even though his emotion and dedication to the choices that he makes causes him to come to blows with his partner and others, there is an affection to their calling him 'half-boiled', and eventually he accepts it as his way of doing things. Despite his flighty exterior Shotaro cares deeply about his clients, his friends, and his city and will do anything in his power to protect them.

Shotaro is a contrast to his partner Philip, showing great capacity for emotion and empathy as opposed to Philip's cold and logical thinking. Because of his emotional side, he is capable of understanding the emotions and actions of others. It is continual exposure to Shotaro's emotional nature that leads to Philip warming up to his own emotions. Due to his aspiration to be hard-boiled, Shotaro usually tries to be the serious and cool-looking one in his group, but that often results in him often being the one who is being made a fool of by others, his friends and enemies alike. Shotaro takes the role of Kamen Rider Double very seriously and with great pride, as the name "Kamen Rider" was given to them by the citizens of the city themselves. As such, he tries very hard to make a good name for Kamen Rider Double, and live up to expectations that came with the title.

He is fond of anything retro and this can seen from what he wears to he uses. He is rarely seen wearing anything that is not a set consisting of a dress shirt, a pair slacks, a necktie, a waistcoat and most importantly (to him at least), a fedora hat. He is always seen typing on a typewriter for case-filing purposes, despite having a laptop in the hangar. His bike helmet is also a retro-styled one. His fondness for retro-styled items is so intense that one can say that his use of anything modern is only out of necessity.

Shotaro has a habit of flicking his left wrist in the air before and during battles, similar to Takumi Inui's habit of flicking his right wrist at his side after transformation.

Abilities
Being trained by Sokichi for years, he has honed his detective skills enough to become a competent private detective who is able to solve cases even without the help of Philip. He has a keen eye for details and has good deductive intuition, as such he is able to piece information together quickly and coherently and thus rarely fails in determining the culprit behind cases. His skills is such that the police, specifically Ryu, would often come looking for his help when dealing with Dopant cases.

Oddly enough, he has also shown a great skill in locating pets easily, more so than finding people, first seen when trying to locate a cat not knowing it was a trick and finding Mick. As a result, he has developed a fame out of it and most of his clients sought him out so to locate their lost pets, to his chagrin.

In combat, Shotaro proves himself to be a competent fighter even without using Gaia Memories, being able to take on several Masquerade Dopants without having to transform. Even in a weakened state of becoming an old man due to the Old Dopant, he is still able to make use of whatever motor skills and stamina left in his deteriorated body to put up a good fight.

Gaia Memories
The Gaia Memories (ガイアメモリ) are mysterious USB flash drives imbued with the powers of the Earth itself. Originally created by Shroud after leaving the Sonozaki Family's Museum organization, these Gaia Memories end up in the possession of Shotaro and Philip, and can only be used through the Double Driver or a Lost Driver. Two can be inserted into the Double Driver, allowing Shotaro and Philip to transform into Kamen Rider Double. Shotaro's left-half Memories called Body Memories (ボディメモリ) determine the type of attack or weaponry that Double uses.


 * Joker Memory (ジョーカーメモリ): The Joker Memory, also known as the Trump Card Memory (切札の記憶), allows the user to increase fighting potential, becoming the Skill Warrior (技戦士). When used, half of Kamen Rider Double becomes the black Trumping Left Half (切り札の左半身). When the Joker Memory is placed in the Maximum Slot on the Double Driver, it allows Double to execute the Joker Extreme Rider Kick. Shotaro can also use the T2 version of the Joker Memory with a Lost Driver to become Kamen Rider Joker. Later, after T2 Joker memory dissolved and Philip disappears, Shotaro use the original Joker Memory to transform into Kamen Rider Joker.


 * Metal Memory (メタルメモリ): The Metal Memory, also known as the Steel Memory (鋼鉄の記憶) or the Fighter Memory (闘士の記憶), empowers the user with great strength, becoming the Superpowered Warrior (怪力戦士). When used, half of Kamen Rider Double becomes the silver Fighting Left Half (闘士の左半身). First used in All Riders vs. Dai-Shocker.


 * Trigger Memory (トリガーメモリ): The Trigger Memory, also known as the Sniper Memory (銃撃手の記憶), turns the user into an expert marksman, becoming the Gun Warrior (銃戦士). When used, half of Kamen Rider Double becomes the blue Sniping Left Half (狙撃手の左半身).

Kamen Rider Joker
"Joker!"

- Transformation announcement

Ability Perimeters: Through the power of the T2 Joker Memory and the Lost Driver, Shotaro uses the power of the Joker Memory to its full potential. When the Memory is placed into the Maximum Slot, Joker executes either a Rider Punch or Rider Kick Maximum Drive. Along with Kamen Rider Cyclone, the two can execute Double Rider Kick Maximum Drive. This form is lost after the T2 Joker Memory is taken by NEVER; But, after Philip dissolves into data and becomes one with the Earth, Shotaro finds in the present Philip gave to him, the Lost Driver from the incident. He uses his original Joker Memory in place of the T2 Joker memory to become Kamen Rider Joker again. However, one year later, Shotaro is overwhelmed by the newly formed EXE group until Philip returns. It is shown in Movie War Mega Max, that if he finds Philip is being in middle of one of his obsessions again and too occupied to fight, he will swap out the Double Driver for the Lost Driver.
 * Height: 195 cm.
 * Weight: 85 kg.
 * Punching Power: 1.25 tons
 * Kicking Power: 3 tons
 * Maximum Jump Height: 30 m
 * Maximum Running Speed: 100 m. per 6.2 sec

Lost Driver
With Shotaro unable to use the Double Driver he uses a Lost Driver he received from Skull instead to transform. This Memory Driver was lost in the battle with Kamen Rider Eternal, but Shroud gave Philip another Lost Driver and Philip kept it, which he later gives to Shotaro. To transform, Shotaro places the Joker Memory in the Memory Slot to transform into Kamen Rider Joker.

Gaia Memories

 * T2 Joker Memory: The T2 Joker Memory was one of the 26 T2 Gaia Memories and the first Gaia Memory used by Kamen Rider Joker, both for the transformation and Finisher. The T2 Joker memory was the Sole memory that NEVER was unable to locate during their reign over Futo. However, after being visited by Kamen Rider Skull, Shotaro realizes that the Memory was what created the recent hole in the Agency's ceiling, having been called to him as he was the person that resonated most strongly with it. He then takes the Memory and uses it in unison with the Lost Driver that Skull gave him to combat the T2 Dopants and rescue Philip. However, the T2 Joker Memory was lost when Eternal was able to defeat Joker using the T2 Unicorn Memory to execute his own Rider Punch Maximum Drive. It was then destroyed when Double CycloneJokerGoldXtreme's Golden Xtreme Rider Kick destroyed Eternal, along with all other T2 Gaia Memories.
 * Joker Memory: After the T2 Joker Memory was destroyed and Philip dissolved into data completely, Shotaro uses the original Joker Memory in place of its successor. There is no noticeable difference in Kamen Rider Joker's form or abilities when using this Memory; if anything, it's possible the T2 Memory may grant an increase in basic power.

Portrayal
Shotaro Hidari is portrayed by Renn Kiriyama (桐山 漣). As a child, Shotaro is portrayed by Issei Kakazu (嘉数 一星). Kakazu later portrays Akira Aoyama in the television series' final episode. As a elder in episodes 43 and 44, Shotaro is portrayed by Yukimasa Natori (名取 幸政).

As Kamen Rider Double (and Kamen Rider Joker), his suit actor was Seiji Takaiwa (高岩 成二), who has been the suit actor for the majority of leading Heisei Kamen Riders (except Kuuga and Hibiki).