|This article is about a transformation device in Kamen Rider W.|
The Transformation Belt Lostdriver (変身ベルト ロストドライバー, Henshin Beruto Rosuto Doraibā) is a 2nd Generation Memory Driver used by Sokichi Narumi, Katsumi Daido, and Shotaro Hidari to transform into Kamen Riders Skull, Eternal, and Joker respectively.
Due to using refined Gaia Memories that retain their form rather than be absorbed into the user's body, the user is completely shielded from its corrupting effects. This comes at the cost of the Gaia Memory's power being further weakened except for during a Maximum Drive. As it is a prototype that was later developed into the Doubledriver, forms accessed with T1 Gaia Memories are extremely weak, though the user's personal experience may mitigate this as shown with Shotaro Hidari's fights after Philip's disappearance.
Two more Lostdrivers also existed. One, shown to be in the possession of the NEVER organization leader, Katsumi Daido, which he took from Jun Kazu of Foundation X. The other, given to Philip by Shroud in order to fight Zoo and Zebra Dopants as Kamen Rider Cyclone before he gave it to Shotaro after he sacrificed himself to save Wakana from the Gaia Impact.
The Lostdriver was an early attempt by Shroud to further refine the power of the Gaia Memories, after the success of the Gaia Driver. The first known Lostdriver was given to Sokichi Narumi following by Shroud following her escape from the Museum, though he initially refused it on the principle of fighting with his own strength. Sokichi eventually accepted the gift and used it in tandem with the Skull Memory to transform into Kamen Rider Skull. This Driver disappeared along with Sokichi following Phillip's liberation from the Gaia Tower.
The Dummy Dopant would later use the Dummy Gaia Memory to impersonate Sokichi, including replicating his Lostdriver, during the events of Begins Night. Even later, Sokichi's ghost seemingly appeared in front of Shotaro during the events of Kamen Rider W Forever: A to Z/The Gaia Memories of Fate, leaving his Lostdriver to his former protege. Shotaro used the Lostdriver along with the T2 Joker Memory to become Kamen Rider Joker to battle NEVER, though the Driver was seemingly lost before the end of the conflict.
Another identical Lostdriver was used by Jun Kazu and Katsumi Daido to become Kamen Rider Eternal, using both the original and T2 Eternal Memories, though this one was lost following Daido's destruction. After the destruction of the Museum, Shotaro discovers another Lostdriver left behind for him by Phillip, allowing him to continue protecting Futo using his own power. Despite Phillip's return from the True Gaia Memory a year later, Shotaro still carries the Lostdriver with him should he be forced to fight by himself.
By inserting a Gaia Memory into the Memory Slot (メモリスロット, Memori Surotto) on the belt buckle, a user can transform into a Kamen Rider.
The transformation into a Kamen Rider will be canceled if a Gaia Memory is removed and not re-inserted for a certain amount of time.
Another slot on the right side of the Lostdriver is called the Maximum Slot (マキシマムスロット, Makishimamu Surotto). When a Memory is placed in the Maximum Slot, a Kamen Rider can use a Maximum Drive (マキシマムドライブ, Makishimamu Doraibu) finisher attack.
Users (chronological order)
|User||Kamen Rider||Episode Obtained||Episode Destroyed||Description|
|Sokichi Narumi||Skull: Message for W||N/A||The Skull Lostdriver was given to Sokichi Narumi by Shroud to aid him in his battle against Museum. She may have stolen it from Museum, as hinted by Saeko's reaction to Sokichi using it. After Philip hid the Lostdriver without telling Shotaro, Sokichi's spirit appeared and guided Shotaro to its location.|
|Father Roberto Shijima (As the appearance of Sokichi Narumi)||W: Begins Night||N/A||As the Dummy Dopant, the user can assume any form he wishes. While assuming Sokichi's form, he can also manifest the Lostdriver and Skull Memory automatically, as he uses Skull's form to discourage Shotaro's interference.|
|Jun Kazu||Kamen Rider W Returns: Kamen Rider Eternal||N/A||Jun Kazu was given a Lostdriver and the T1 Eternal Memory from Foundation X, which he used to become Kamen Rider Eternal. However, he was not compatible with the Gaia Memory, so he could only access Eternal's Red Flare Form.
After Jun Kazu was killed by Katsumi Daido, his Lostdriver and Gaia Memory were taken by Daido, who became the second Kamen Rider Eternal.
|Katsumi Daido||Kamen Rider W Returns: Kamen Rider Eternal||Kamen Rider W Forever: A to Z/The Gaia Memories of Fate||Daido took Jun Kazu's Lostdriver and T1 Eternal Gaia Memory after killing him and used them to become Kamen Rider Eternal. He later swapped out the T1 Eternal Gaia Memory for its T2 version.
Daido's Lostdriver was destroyed when he was defeated by Kamen Rider Double at the top of Futo Tower.
|Philip||Kamen Rider W: ~The One Who Continues After Z~||N/A||When Shotaro had fallen sick and was not able to fight, Shroud gave Philip a Lostdriver to use with his Cyclone Gaia Memory and become Kamen Rider Cyclone. After Shotaro recovers, Philip hides the Lostdriver, intending to not use it again.
After sacrificing his physical body to save Wakana, Philip gives his Lostdriver to Shotaro, who had lost his own, in order for him to become Kamen Rider Joker once again.
|Shotaro Hidari||Kamen Rider W Forever: A to Z/The Gaia Memories of Fate
||N/A||Shotaro was given Sokichi Narumi's Lostdriver by the latter's spirit, which he used with the T2 Joker Gaia Memory that he found to become Kamen Rider Joker. He lost this Driver soon after, however, when he was defeated by Kamen Rider Eternal.
Later, Philip gives his own Lostdriver to Shotaro after he had sacrificed his physical body, enabling Shotaro to become Kamen Rider Joker again with his T1 Joker Gaia Memory.
- Kamen Rider Skull (W Episode 13, Movie War 2010 (flashback), A to Z/The Gaia Memories of Fate, Movie War Core, Chou Super Hero Taisen, Kamen Rider Heisei Generations FOREVER (as a toy))
- Kamen Rider Eternal (W Returns: Kamen Rider Eternal, A to Z/The Gaia Memories of Fate, Type HIGH SPEED! (only Image), Kamen Rider Ghost: Special Event, Zi-O Episodes 45-46)
- Kamen Rider Joker (A to Z/The Gaia Memories of Fate, W Episode 49, Movie War Mega Max, Kamen Rider Taisen)
- Kamen Rider Cyclone (Kamen Rider W: ~The One Who Continues After Z~)
- The Lostdriver is simply a standard Doubledriver with the right half of its terminals removed. Nothing replaces the missing terminal, leaving it conspicuously empty.
- It is possible to modify a toy version of the Doubledriver by removing its right terminal to create a Lostdriver. An actual Lostdriver toy was released to coincide with the second film, with no changes besides the aforementioned missing right terminal and only including the Skull and Eternal memories. Either of these can be used with the Joker memory, although the Joker Memory included with the Doubledriver toy is specifically timed to sound off after the left side memory, resulting in a noticeable delay after activation. The T2 Joker Memory toy released as a promotional item for second film does not share this issue.
- It is unknown if the term "Lost" prefix has any particular meaning to the development of the Gaia Memory, as the only known applicable instance was the fact Shroud stole it from the Museum following her escape.