Kouji Segawa

Kamen Rider J (仮面ライダーJ) is the main protagonist in the Japanese tokusatsu movie Kamen Rider J.

Kouji Segawa
Kouji Segawa (瀬川 耕司, Segawa Kōji) is an environmentalist reporter who was investigating the pollution by the lake. He was killed while attempting to protect his young friend, Kana and was thrown over the cliff by the Fog Mother's child Agito as Kana is taken by the insectoid Zu. However, Kouji was resurrected by the Earth Spirits as a J-Powered Warrior, Kamen Rider J, acting on their will to fight the Fog with their emissary Berry as his guide. With Fog Mother sensing Kouji's presence, Agito attempts to finish the job in his true form, only to be killed by J. Hurrying to Kana, Kouji enters their domain and faces Zu as she assumes her true form. Facing her, J manages to mortally wound Zu as she grabs him, taking to before they crash into the fortress which is Fog Mother.

After she dies, Kouji learns of Fog's intention of feeding humanity to as Garai completes the ritual and sends Kana to the hatching chamber while manhandling Kouji. Berry intervenes to free Kana from Fog's spell before being struck down by Garai as Kana is sent down to her death while Fog Mother begins attacking a nearby city to prepare for her children's awakening. Assuming his Rider form, J fights Garai in his true form, Cobra Man, in a heated battle. After killing Garai, J is being digested by Fog Mother as he attempts to save Kana. However, absorbing the life energy around him, J kills off Fog's newly born spawn as he escapes the bowels of Fog Mother and assumes Jumbo Formation. After ripping Kana out of Fog Mother, J battles the monster before killing her as she attempted to take him down with her. Escaping Fog Mother's destruction, Kouji takes Kana to a serene environment with Berry watching from a distance.

Kakuranger Stage Show at Super Hero Korakuen Yuenchi
In a stage show where the Kakurangers are seen fighting theirusual foes, a the bandora gang, the goma tribe, and fog show up and wind up defeating them. Kamen Rider J, RyuuRanger, HououRanger, TyrannoRanger, & DragonRanger arrive assit the Kakurangers.

Kamen Rider World
Later, J teamed up with Kamen Rider ZO. The two riders fought a gang of five revived monsters led by Shadow Moon: Sai Mutant, Cyborg Soldier Lv. 2, Agito, Garai, and Zu. Berry witnessed Shadow Moon's plot and is attacked by the mutants. Masato and his sister Ayumi stumble onto an injured Berry by chance and are chased by the revived mutant army as a result.

However, they are saved by the sudden arrival of Kamen Rider ZO on his ZO Bringer motorcycle, who thwarts off the monsters into a nearby abandoned warehouse. ZO is suddenly assisted by Kamen Rider J, who arrives into the warehouse on his J Crosser bike. The five mutants are defeated by the combined forces of the new Double Riders. The two are then challenged by Shadow Moon, who enlarges himself into giant proportions. J grows into giant size as well and fights off Shadow Moon by himself. Shadow Moon is defeated and peace returns to the day.

Decade: Final
He fought Tsukasa (Kamen Rider Decade) in Jumbo form, but defeated mercilessly without any attacks from him damaged Tsukasa.

Let's Go Kamen Riders
A mishap caused by the Greeed Ankh unintentionally altered the timeline which enabled Shocker to utilize the Core Medal to create the Shocker Greeed which defeated the Double Riders and seemingly erased the legacy of the Kamen Riders from history. In 2011, after Kamen Rider New Den-O's attempt to repair the damage, he along with Kamen Rider OOO and M-Ankh awaited execution. However, it was revealed the Double Riders had their brainwashing removed by a Shocker scientist.

The Double Riders joined with New Den-O and OOO to fight Shocker's forces, but were eventually defeated. When the order was given to kill everyone, V3 suddenly appeared, asserting that there were more than four riders. V3 was soon followed by all the other revived riders that came after him, including J, as even though Rider history was changed, the people's memories haven't changed.

After the riders were united, they faced off against Shocker's Great Leader. Later, when joined by a force of extra riders, J and all the other riders got on their motorcycles and performed the "All Rider Break", ramming into the Rock Great Leader and defeating it once and for all.

Rider Form
Kamen Rider J primary form. In this form Kamen Rider J has the ability to execute the J-Kick.

Jumbo Formation
By harnessing the lifeforce from the surrounding life forms, Kamen Rider J can grow into a giant size at 40 metres tall (the largest size he has used) to fight against larger opponent. In this form Kamen Rider J has the ability to execute the Jumbo Rider Kick.

J-Spirit
The J-Spirit is Kamen Rider J transformation belt.

J-Crosser
The J-Crosser is a Suzuki off-road bike that Kamen Rider J rides on. It has the ability to reach a speeds up to 1300 km/h. Kamen Rider J also can use the J-Crosser to execute the J Striker attack.

Kamen Ride Cards
Kamen Ride J (カメンライドJ) is the Kamen Ride Card which contains the power of Kamen Rider J. In All Riders vs. Dai-Shocker, Decade Complete Form Jumbo Formation performed the Final Dimension Kick, a variation of the Dimension Kick, transforming the Shōwa Riders, including J, and Heisei Riders into Kamen Ride cards for Decade to travel through as opposed to Final Attack Ride cards before hitting the target.

In theory, this card would allow Kamen Rider Decadetotransform into J.

Other Appearances
Although Yūta Mochizuki has never returned to portray the character Kouji Segawa, the "Kamen Rider J" character has appeared in later Kamen Rider/Super Sentai live action productions.

Kakuranger Stage Show at Super Hero Korakuen Yuenchi
In a stage show where the Kakurangers are seen fighting their usual foes, the Bandora gang, the Gorma tribe, and Fog show up and end up defeating them. Kamen Rider J, RyuuRanger, HououRanger, TyrannoRanger, & DragonRanger arrive to assist the Kakurangers.

Kamen Rider World

 * Kamen Rider J later team-up with his predecessor, Kamen Rider ZO, in the 8-minute movie Kamen Rider World.

Kamen Rider Decade: All Riders vs. Dai-Shocker

 * Kamen Rider J later appears in the 2009 film Kamen Rider Decade: All Riders vs. Dai-Shocker. In the film's climax, he is summoned, in giant form, by Kamen Rider Diend to battle with King Dark. With Diend's help, he merges with Kamen Rider Decade to form Kamen Rider Decade Final Form Jumbo Formation. The Internet movies released with this film identify J as the 15th official Kamen Rider of the Showa era.

Kamen Rider × Kamen Rider W & Decade: Movie War 2010

 * Kamen Rider J also appears in the 2010 film Kamen Rider × Kamen Rider W & Decade: Movie War 2010, fighting Kamen Rider Decade, only to be defeated and turned into a card by him. After Decade's eventual defeat, it is revealed that all the Riders he turned into cards are restored to their respective worlds; J's is presumably one of them.

OOO, Den-O, All Riders: Let's Go Kamen Riders

 * Kamen Rider J (in Rider form) appears in OOO, Den-O, All Riders: Let's Go Kamen Riders. He reappears alongside the other Heisei era Riders.
 * Although J's human form isn't shown in the movie itself, he has no lines and isn't listed in the credits, J is confirmed to be Kouji Segawa by the movie's official website.

Video Game

 * Kamen Rider J is a playable character the 2011 Nintendo DS video game All Kamen Rider: Rider Generation.

Portrayal
In Kamen Rider J, Kouji Segawa was portrayed by Yūta Mochizuki (望月 祐多). As Kamen Rider J, his suit actor was Jiro Okamoto (岡元 次郎).
 * In Kamen Rider Decade: All Riders vs. Dai-Shocker, his suit actor was Jiro Okamoto (岡元 次郎) once again.
 * In Kamen Rider Decade: The Last Story, he was voiced by Kouta Nemoto (根本 幸多), his suit actor was once again Jiro Okamoto (岡元 次郎).
 * In OOO, Den-O, All Riders: Let's Go Kamen Riders, J was voiced by an unidentified voice actor and portrayed by an unidentified suit actor.
 * In Kamen Rider × Super Sentai: Super Hero Taisen, J was portrayed by an unidentified suit actor.

Trivia

 * Yuta Mochizuki, who played Kouji Segawa, also played Yamato Tribe Prince Geki, one of the protagonists from Kyōryū Sentai Zyuranger.
 * Interestingly, Kamen Rider J closely resemble Kamen Rider ZO.
 * This is because the producer of the two films wanted the two to be the new Double Riders.
 * Kamen Rider J's ability, Jumbo Formation closely resembles Ultraman, the difference is when Ultraman changes he automatically transforms into a giant. Another difference is Ultraman is powered by light and can only fight for a short period of time, while J is powered by the life energy of the Earth and can fight for as long as he wants in Jumbo Formation.

Also see
Dex Stewart, his counterpart in Saban's Masked Rider.