Sokichi Narumi

Kamen Rider Skull is a Kamen Rider first appearing in Kamen Rider × Kamen Rider Double & Decade: Movie War 2010. He then makes appearances Kamen Rider × Kamen Rider × Kamen Rider The Movie: Cho-Den-O Trilogy in the Episode Yellow film, a music video for Nobody's Perfect, and in Kamen Rider Double Forever: A to Z/The Gaia Memories of Fate and a starring role in the Kamen Rider Skull: Message for Double portion of Kamen Rider × Kamen Rider OOO &amp; W Featuring Skull: Movie War Core.

Background
Sokichi Narumi (played by Koji Kikkawa) was Shotaro's mentor (whom he refers to as "boss"), Akiko's father, and founder of the Narumi Detective Agency in the fictional Futo City. While working as a private investigator, he was partnered with a man similar to his protege Shotaro Hidari's partner, Philip named Seiichiro Matsui (nicknamed Matsu) and had the personal mantra to keep the client safe at all costs. He also provided his childhood friend Fumine Sonozaki (now Shroud) refuge after she was forced to leave her family and take up her new identity. After an encounter with the Spider Dopant, a young Shotaro became interested in him and back at the agency, Shroud while working on the hangar (which would become the SkullGarry) gave him the Skull Memory.

Sokichi then encounters the Spider Dopant again, this time with the Bat Dopant and when Shroud throws him the Lost Driver, he transformed into Skull Crystal in order to fight back. Later when he found out that the Spider Dopant is Matsu, Skull fought his partner and the Bat Dopant, revealed to be the Gaia Memory Dealer, Eren Komori where he destroyed both of their Gaia Memories and Matsu dying after the Memory Break. Despite his crimes, Sokichi still called Matsu his partner and walked away. Since the incident, Sokichi took the motto "Now, count your sins!" to heart because he saw himself to be unable to realize his ex-partner's madness and stop it before the city suffers as a result. Furthermore, unlike the others victimized by the Spider Dopant, Sokichi's Spider Bomb did not fade in the Spider Memory's destruction and he decided to isolate himself from Akiko to ensure her safety. After this, Sokichi became involved in investigating cases involving Dopants that the police force could not handle, including the armored car robberies performed by the "Beastman".

Eventually taking on Shotaro Hidari as his protege, Sokichi agrees to help Shroud stop the Museum by infiltrating a research facility known as the Gaia Tower with Shotaro in order to find the young man at its center. After fighting several Masquerade Dopants and the Taboo Dopant, he and Shotaro find the young man as Narumi offers him freedom to find atonement for his part in the creation of the Gaia Memories, naming him Philip after his favorite fictional character Philip Marlowe. After Narumi frees Philip from the Gaia Tower and begins to take both him and Shotaro out of the building, he is shot by several armed guards. As he dies, he gives his white fedora to Shotaro and asks for Shotaro to become a man worthy of wearing it. It was after the Gaia Tower fell into ruins that Shotaro and Philip, spurred by his advice to continue in his place, learn that Sokichi's body is no where to be found.

In Begins Night, Sokichi Narumi and Kamen Rider Skull are among the identities taken by the Dummy Dopant while pretending to be the Death Dopant in a scheme to assume the identities of Futo's upper class members, using Sokichi's form to drive Shotaro off from the case before he realizes the truth. However, Shotaro finally overcomes this and Double ultimately defeats the imposter Kamen Rider Skull. After the case is concluded in Movie War 2010, Tsukasa Kadoya uses a Kamen Rider Skull card he has acquired to summon an iteration of Sokichi Narumi from an alternate dimension, giving Shotaro closure. This Sokichi does not seem to know Shotaro but recognizes the very thing that the real Sokichi wanted of Shotaro: for Shotaro to become a true detective.

Kamen Rider Skull's final appearance is in Kamen Rider W Forever: A to Z/The Gaia Memories of Fate where he gives Shotaro his Lost Driver before fading away as he takes his leave, enabling Shotaro to transform into Kamen Rider Joker. The Skull Memory is also one of the 26 T2 Gaia Memories in the film.

Kamen Rider Skull made an appearance in the film Kamen Rider × Kamen Rider OOO & W featuring Skull: Movie War Core, with his daughter Akiko finding out the full story behind Narumi becoming Skull through one of the Pteranodon Yummy and the Memory Memory.

Kamen Rider Skull
With the use of the Lost Driver and the Skull Memory, Sokichi transforms into Kamen Rider Skull. Skull is unique in that besides wearing a white tathered scarf he also wears a white fedora. It is revealed that he was original user of the quote "Now, count your crimes!" (さあ、お前の罪を数えろ！, Sā, omae no tsumi o kazoero!?), a quote now used by his successor. Skull's motif is that of a human skull and the letter S. Like Skull Rider, Skull appears to be a homeage to Skull Man, Shotaro Ishinomori's previous creation, who was adapted for the creation of Kamen Rider 1. Skull is shown to be a powerful fighter, able to fight equally with the Terror Dopant (as shown in the "Nobody's Perfect" music video) whereas other riders had difficulty combating him, and is able to use the Skull Memory's powers to full effect. As shown in Episode Yellow in the Cho-Den-O Trilogy, Skull's Maximum Drive, without a weapon is a Rider Kick. In Skull: Message to Double, Skull also reveals to have another Maximum Drive that involves releasing a giant energy skull from his chest and after putting the Skull Memory into the Maximum Slot, Skull jumps up and does a roundhouse Rider Kick to propel the skull toward an opponent.

Skull Crystal
Kamen Rider Skull Crystal (仮面ライダークリスタルスカル, Kamen Raidā Sukaru Kurisutaru?) is the incomplete form of Skull that first appears in the events of Kamen Rider × Kamen Rider OOO &amp; W featuring Skull: Movie War Core. It differs from Kamen Rider Skull's standard form in that the helmet is iridescent and it lacks the S-shaped "crack". Skull Crystal is able to attack by releasing energy from his chest in the shape of a large purple skull that can bite opponents. This form is named after the crystal skulls.

Lost Driver
The Lost Driver is Skull's transformation belt. Sokichi received this from Shroud to combat Dopants easier. It is similar in design to the Double Driver used by Double.

Gaia Memories
Skull Memory: The Skull Memory also called the Skeleton Memory is the Gaia Memory used for the transformation into Kamen Rider Skull and for Maximum Drives, when placed in the Maximum Drive slot, it performs the Skull Banisher Rider Kick

Skull Magnum
The Skull Magnum is a firearm similar to the Trigger Magnum in Maximum Mode used by Double. It is gained through the power of the Skull Memory its Maximum Drive called the Skull Punisher which blasts the opponent with powerful rapidfire shots.

SkullBoilder
Skull also has a modified Honda CBR1000RR motorcycle similar to Double but is all black in color, and it is armed with the Universal Launcher (ユニバーサルランチャー, Yunibāsaru Ranchā?) guns.

SkullGarry
The SkullGarry (スカルギャリー, Sukarugyarī?) is a tank/garage that holds the SkullBoilder. It was created by Shroud and the vehicle later becomes Kamen Rider Double's RevolGarry after a redesign at the front. The SkullGarry only appears in the Kamen Rider Skull: Message for Double portion of Kamen Rider × Kamen Rider OOO & W Featuring Skull: Movie War Core.