Shouichi Ashikawa

Shouichi Ashikawa (芦河 ショウイチ) is the resident Kamen Rider of the World of Agito in Kamen Rider Decade.

History
He is a young man who supports the police, originally the user of the G3 system that was designed to fight the Gurongi. However, he mysteriously metamorphed into Kamen Rider Exceed Gills, a larval form of Agito. Hunted by the Lords, Shouichi left the force without explaining his reasons, the isolation he placed on himself making him antisocial. However, the real reason is actually because he doesn't want his presence endangering Toko. The pain of the changes inside his body worsen whenever he senses the presence of nearby Lords attacking humans.

Possessing a year-old letter for him from Toko, Tsukasa and Natsumi arrive to his long dilapidated home to give him his letter, only for them to be followed by a Formica Pedes. Amazed at Decade's power, he rips the letter Tsukasa gives him and tells him to stay away from him as they are nearly killed by an attack from the Buffalo Lord Taurus Ballista. After reading the letter, Tsukasa finds Shouichi and offers to protect him from the Lords. This however, enrages Shouichi as he becomes Gills with Tsukasa restraining him before he runs off to where a pair of Pedes are fighting Yusuke and Diend.

After killing the monsters, Gills is targeted by Diend until Decade arrives to protect him. However, Gills takes the Decade Belt as he runs off when Ballista himself appears with his Ant Lord minions. Though he refuses Tsukasa's aid, it takes Yusuke's interference to help Shouichi realize Toko knew why he ran off and loves him enough to protect him by creating the G3-X Suit. This revelation allows Shouichi to complete his evolution into Agito, supporting Decade and G3-X in defeating the Unknown. Soon after, Shouichi returns to the police force to support them as Agito.

When Tsukasa goes into the World of the Rider War, the only "Rider Worlds" remaining are of Blade's, Kiva's and Hibiki's. It is revealed that Agito's world has vanished like the other worlds.

During Movie War 2010 events, he is revived after Decade's death and helps revive Decade. He later appears to help in the final battle with Super Shocker, transforming into Shining Form as a result of Decade's K-Touch and later into his Agito Tornador form with the All Rider Final Form Ride Card to fight the Super Crisis Fortress.

Later appearances
Movie War 2010 currently remains the last appearance of Shouichi Ashikawa. The Agito that appears in OOO, Den-O, All Riders: Let's Go Kamen Riders and Kamen Rider × Super Sentai: Super Hero Taisen is the original Agito, Shouichi Tsugami.

Rider Powers
Shouichi also possesses some of the same equipment used within the original Agito, such as the Alter Ring (オルタリング) transformation belt, which holds the "Seed of Agito" that serves as the source of his power. Kamen Rider Decade's Final Form Ride allows him as Agito to change into Agito Tornador (アギトトルネイダー), a hoverboard similar to the Machine Tornador in Slider Mode.

Before he assumed the title Agito, he previously assumed the title Kamen Rider Exceed Gills (on his first appearance) and Kamen Rider G3 (as shown in Kamen Rider Decade episode 13)

Portrayal
Shouichi Ashikawa is portrayed by So Yamanaka (山中 聡), previously Kamen Rider Kirameki in Kamen Rider Hibiki & The Seven Senki and who would later portray in . As Kamen Rider G3, Kamen Rider Exceed Gills, and Kamen Rider Agito, his suit actor is Jun Watanabe (渡辺 淳).

Etymology
NaNs
 * Shouichi Ashikawa (芦河 ショウイチ) is a of the three main characters in the Kamen Rider Agito series, with his name being a  of all three characters' names: Shouichi Tsugami (津上 翔一) (Agito), Ryō Ashihara (葦原 涼) (Gills) and Makoto Hikawa (氷川誠) (G3).
 * This is played further as he donned the G3 suit and assumed the form of Exceed Gills before becoming Agito.