|Makoto Hikawa is a cop chosen to use the G3 System to battle the Lords, whom his superiors labeled as "the Unknown", and keep them from murdering people. Hikawa is an earnest, straight forward, and honorable man, though slightly naive and clumsy. Because he was regular human, the Lords usually ignore him; but sometimes are surprised that a normal human being can wield such power. One day, while on patrol, Hikawa witnessed the Akatsuki being held by the El of the Sea, taking a boat to investigate and save all but one of its passengers. Because of his role in the incident hero further showed his skills in a crisis, Hikawa was assigned to the G3 Unit. Because of his naivety, Hikawa is always get troublesome by Shouichi to helping him doing house work.
Hikawa got transferred to criminal investigations for a short while until he proved his skills by anticipating the Zebra Lords' next target, resuming his role in the G3 squad while decking Hojo when he attempted to capture Agito. After investigating the house of Professor Nobuyuki Kazaya, Hikawa finds a video tape hidden in one of the building's supports along with an inside-out tennis ball. Though it took a while, Hikawa learns that there is a message in the audio. Hikawa arrives to the scene of a mysterious murder of a member of the Agito Capture Plan group, identical to the death of Nobuyuki Kazaya. Once learning the connection to another group member, Higawa warned Hojo before he was attacked by Aki and lived to tell it. After that, Hikawa guards Honjou as he questions the moral implications of humans having such power before being deployed to stop the fight between Agito and Gills, only to nearly killed by the stronger riders. As a result, a new stronger battle suit is needed to fight against the stronger riders and Unknown.
Hikawa was given the upgraded G3-X Suit that is better suited for Unknown Combat and "perfect" in every way. However, the perfection was the flaw as AI would momentarily takeover an impure wearer, as seen when the suit acted on Hikawa's deepest desires when it took control. After consulting her mentor, Ozawa installs a special inhibitor chip to regress the AI. Hikawa finally learn the true identity of Agito in episode 39 when he de-transformed in front of him after being knocked by Another Agito, and Hikawa was visibly shocked to learn Agito is Shoichi, much to his disbelief makes him losing his cool, even getting in short argument with Ozawa and almost mauling Omuro while in G3-X, disappointed on the revelation and can't accept it at first. Because the true identity of Agito he admired was far away from what he expected. This caused Hikawa to be hesitant on meeting Shoichi. However after the two combining they effort to defeat Skelos Glaucus causing them to continue their usual relation. And Hikawa became more respecting of Shoichi. After Hojo took over the G3 Unit with a reformed method of protecting the Unknown instead, Hikawa was transferred back to Kagaki-ken. However, Hikawa couldn't leave just yet, so he and Ozawa took back the G3 Unit. Donning the G3-X one final time, Hikawa aids Agito and Gills in finishing off the Lords for good. By the next year, Hikawa leaves the G3 Unit and returns to being a normal officer of the law.
In light of the threat of he Grongi, Tokyo's Metropolitan Police Department Strike Against Unidentified Lifeform received funding from the city government to develop a powered, reinforced exo-suit based on the No.4 Unidentified Lifeform, Kuuga to respond to the menace. However, because the Grongi was eliminated long before completion, research on the project was postponed indefinitely. By this time, the data acquired from the G1 and G2 had been implemented into the Generation-3 (3rd generation exo-armor), which was entering its final phase of development, ready for live-combat deployment. But with the emergence of the Lords, the G3 unit was reinstated and decommissioned to contend with the threat. Its most potent armament is the GG-Launcher (GG-02 Salamander). Using the testbed G3 suit, Sumiko Ozawa went through with the development of this highly-modified exo-armor, using the G3's diagnostic data. All specs and performance potentials have been ramped-up. However, a newly installed AI interface would pose a very serious risk on the operator. The AI's calculations, though perfect, requires precise coordination and synchronization with the suit motor functions. To this end, only an operator with clear consciousness can operate it without being physically taxing on the body. To this extent, the suit was made 'too perfect'. However, in light of this, a new control chip with a modified 'scaled-down' AI was installed to make the suit less demanding. Its newest armament, the GX- Launcher (GX-05 Cerberus), can level an Unknown with ease. The test model for a mass-production G3 exo-suit is the Generation-3 Mild. The automatic fitting function that was featured on the G3 System was improved for universal equipping. However, funding and support was inadequate, despite plans from the Tokyo Metropolitan Police to mass-produce G3-Mild systems and organize a G3 strike force. On an interesting note, to prove that anyone could operate the G3-Mild system, Takahiro was elected as the initial operator and has worn it on two occasions.