Kengo Utahoshi

Kengo Utahoshi (歌星 賢吾, Utahoshi Kengo) is the lead supporting protagonist in Kamen Rider Fourze, acting as the partner for the lead protagonist, Gentaro Kisaragi. He is also the original owner of the Fourze system until he gave it to Gentaro to become Kamen Rider Fourze due to his weak health. He was also the first Powerdizer pilot to assist Fourze in battle, but his stamina limited his tenure until Shun Daimonji was recruited.

Pesonality
Kengo is a loner with a strong will and wants to follow through with his father's plans to fight the Zodiarts. Because of this, he tries remains distant from people to not get them involved. Kengo does however accept help from Yuki Jojima and Gentaro after some convincing. He is willing to go to lengths that puts him and his health in danger which limits his actions. Kengo does not acknowledge the existence of the Kamen Rider Club and refuse to be a member of the Club. Though he is Gentaro's partner, he insists that Gentaro refers to him by his surname instead of his given name, and much to his chagrin, Gentaro refuses to do so.

He eventually softens as he comes to view Gentaro as friend, instead of merely a necessary partner, calling him at times by his given name instead of his surname, although still refuse to call himself a member of the Kamen Rider Club and gets annoyed when Gentaro calls him by his given name. After he gets trapped on the Moon and he is saved by Gentaro and the others, he sees how serious they are in fulfilling his dream of fighting the Zodiarts, even in his absence. When he is finally saved, he acknowledges the existence of the Kamen Rider Club and joins it, accepting Gentaro and the others as friends. Though Gentaro's antics still irk him somewhat, he is later seen to be more willing to put up with Gentaro's seemingly-stupid plans.

History
Despite looking human, Kengo is actually a Core Child (コアチャイルド, Koa Chairudo), a construct of Cosmic Energy created by the Core Switch (コアスイッチ, Koa Suitchi), one of many mysterious crystal-like Switches that the Presenters sent across the cosmos in search of sentient life who can reverse engineer it. The Core Switch ended up on the moon where it was found by OSTO scientists Rokuro Utahoshi and Mitsuaki Gamou, both respectively creating the Astroswitches that function with the Fourze Driver and the Zodiarts Switches that forcefully evolved humans. A day before Gamou betrays him, Rokuro witnesses the birth of Kengo. Later, guilty of helping Gamou destroy the lunar station and killing Rokuro and unware of the infant's true nature, Kuniteru Emoto found Kengo and brought him to Earth.

A year before the series started, Kengo received a letter and an Astroswitch from an anonymous person. The portal connecting to the Rabbit Hatch lunar base, which is all that remained of the OSTO complex, was opened in the locker in a abandoned club activity room when Kengo just so happened to throw the activated Switch inside. He discovered all about the Astro and Zodiarts Switches on the base and decided to follow through with his father's plans to fight the menace that is to come.

In his third year, having finished the Cosmic Switch, Kengo learns that Tachibana is the one who gave him the Gate Switch as he begins to learn more of his father from Emoto and Gamou during his trip to Kyoto. Eventually, Kengo learns that Emoto is both the Virgo Zodiarts and Tachibana as he reveals to the boy the full story behind his father's death and that the Horoscopes must be stopped from having all twelve switches. During the incident with the Gemini Zodiarts that followed, Gamou noticed a power emitting from Kengo. From learning the contents of Emoto's flash drive, Kengo learns that of his true nature as a Core Child and negate the 12 Horoscopes Switches, thwarting Gamou's plan to seek the Presenters.

Now able to use the Fourze Driver, Kengo reveals to the others that he must leave for the Presenters' planet with everything he has learned about Earth and humanity. Though acting emotionless, Gentaro saw through Kengo's attempt to lessen the pain by severing all ties and tells Kengo that he is still a person and a dear friend. However, as his departure would ruin everything he worked for with The Hole negated, Gamou uses his Sagittarius Nova to stop Kengo from leaving and crush the Core Switch, causing Kengo's body to dissolve into particles of light.

After Sagittarius Nova's defeat, upon finally accepting Gentaro's friendship, Gamou has spend his final moments before being evaporate into stardust while used the Aquarius's power to recreating the Core Switch, allowing to resurrecting him and reunited with his friends.

Role in Story
Kengo is a second year student at Amanogawa High School who is physically weak but has a strong will. Upon meeting Gentaro and an encounter with the Orion Zodiarts, he gave him the equipment to become Fourze, such as the Astroswitches and Machine Masshigler, and acting as his tactician.

Abilities
Kengo is intelligent by manner unrelated to school work, having a vast amount knowledge of the Astro and Zodiarts Switches and the Powerdizer which is useful in battle. Unfortunately, Kengo alone is highly unsuited for combat due to his weak body which prevents him from using the Fourze System. To compensate he uses the Foodroids and the Powerdizer to fight, but even then using the Powerdizer for a long period of time is an extremely difficult task for him due to the stamina needed to move. Because of his condition, the Fourze Driver was given to Gentaro and the Powerdizer to Shun Daimonji.

During the situation Gentaro was poisoned and unable to fight, Kengo uses an unnamed temporary module which have the same ability as the Square Astroswitch Basement, suggested by Tomoko. It links up to the Fourze Driver and can allow him to use Astroswitches without transforming into Fourze, but he will suffers the great strain on his body.

More recently, Kengo was able to nullify the power of all twelve Horoscopes Switches by awaken his powers thanks to him being the Core Child.

Fourze Arsenal

 * Main article:Fourze Arsenal

The entirety of the Fourze arsenal technically belongs to Kengo, constantly developing the system his adopted father made which he is meant as the Core Child to present to the Presenters.

Linkup

 * Main article:Astroswitch Kaban

Many items in the Fourze arsenal are linked up to the Astroswitch Kaban. The Kaban serves as a wireless computer that allows analyses, communication and other functions.

Foodroids

 * Main article:Foodroids

The Foodroids are functional spy devices and utility gadgets that aid the Kamen Rider Club. They have a limited amount of AI that allows them to respond to their human companions by way of performing tasks. They also on some occassions have shown initiative to perform tasks that fall under their set of abilities. They are activated by using specific Astroswitches.

Etymology
Kengo is named after Takeshi Hongo, better known as Kamen Rider #1. His name being an anagram for the Rider's identity (Takeshi Hongou; Takeshi Hongou). Also, his surname Utahoshi contained the kanji "星", which translates into "star" to foreshadow his identity as the Core Switch.