Kiyoto Maki
Kiyoto Maki (真木 清人, Maki Kiyoto?) is a scientist, one of the Kougami Foundation's finest, having devised the Medal System and placed in charge of the Kougami Biotech Laboratory (鴻上生体研究所, Kōgami Seitai Kenkyūjo?). He is at odds with Kougami in just about everything, from the ideology and principles they uphold (Kougami's obsession with beginnings versus Maki's for endings), to concrete matters regarding the Medals, like choosing the container for all the Core Medals and who should be the one to use the Birth system. He initially decides not to go against Kougami's wishes, as Kougami is the one financing all his research and, unbeknownst to Kougami, his schemes. In his youth, he was obsessively attached to his older sister and guardian Hitomi Maki (真木 仁美, Maki Hitomi?), who, despite his affections, was cruel to him and disgusted with him, telling him at their parents' funeral that the true value of something was only evident when it has ended. This statement would come to define Maki's worldview. The day before her wedding, Hitomi gave Maki a doll which he named "Kiyo-chan" (キヨちゃん, Kiyo chan?) to view as a surrogate for her, since he had extreme difficulty talking to anyone but her. That night, driven mad by her intent to abandon him once married, Maki killed Hitomi by causing a fire in her bedroom, burning Kiyo-chan's hair off in the process. Following this, he suppressed almost all memory of both the incident and negative impressions of Hitomi, convincing himself that the fire was an accident and that Hitomi had been a kind and loving sister. Since then, Maki tends to look at his prized doll Kiyo-chan whenever he speaks to someone, making it seem like he is instead conversing with the doll. This tendency is so strong that Maki often becomes unable to speak properly and loses his normally deadpan composure when Kiyo-chan falls from his shoulder. During the middle part of the series, his obsession with cleanliness and Kiyo-chan's occasional acts of supposed supernatural nature becomes a running gag, particularly during his interactions with Akira Date. Since Maki absorbed the purple Medals, Kiyo-chan has been shown in increasingly jarring poses and actions, even once channeling the same Greeed powers as Maki himself, implying some level of sentience.
Though he develops the Kamen Rider Birth System for humans to use Medals like Kamen Rider OOO, Maki soon became more intent on studying the Greeed. Upon being discovered in turn by Kazari, the two set up a partnership to discover if one Greeed could be the holder of all the Core Medals. While Kazari wishes to remain in control of himself during this fusion, Maki wants his partner to become a rampaging Mega Greeed and bring the world to an end. After seeing a restaurant pamphlet with her picture on it, Maki develops an obsession with Chiyoko Shiraishi due to her resemblance to Hitomi. At around this time, Kougami threatens Maki to end his partnership with Kazari, and Maki's strained relationship with the Greeed leads to the creation of the Shachi-Panda Yummy from the man's unfulfilled desire for maternal affection. Maki himself claims this is not indicative of his full motives, as affection is a mere desire, while his goal to end the world is instead a sacred mission, something a mere Greeed like Kazari, driven by desire, cannot understand. Attempting to deal with his own Yummy using Candroids, Maki is wounded and ends up being taken care of by Chiyoko. Maki then takes Chiyoko back to his childhood home, where he reveals to her his story of what had happened. However, being faced with Chiyoko's genuinely kind demeanor causes his mental blocks of his sister's true nature and the origin of the fire to shatter. The result is an abrupt cessation in his desire for affection and a reaffirmation of his belief that the world should be ended while there is still some good left in it. Maki remotely calls hundreds of Candroids to himself with many of the flying ones carrying the painting in his office, activated his lab's self-destruct system to destroy all his research data, and leaves the Kougami Foundation, joining Kazari and Ankh (Lost) as a new man in his quest for the world's destruction. He soon absorbs five of the purple Core Medals, stolen from the Foundation, succeeding in becoming a Greeed himself known as the Kyouryu Greeed (恐竜グリード, Kyōryū Gurīdo?). However, Maki now needs the five Core Medals Eiji has to complete his transformation so when one of the Greeed goes berserk and destroys the world upon becoming complete, he can destroy it and become the last living being on Earth, indulging in the resulting emptiness. After making a deal with Ankh, willing to follow his plan if it means completing his own, Maki steals the Core Medals in Kazari's body after he is heavily injured in a fight with Kamen Rider OOO and leaves him to die. He then gives the pilfered Medals to Ankh, only to be disappointed when Ankh expresses more ambition than just the desire to be complete when he takes only Kazari's Medals. This forces Maki to take matters into his own hands by mortally wounding Gamel and then speeding up Eiji's Greeedification, to convince Eiji to relinquish the purple Core Medals, before deciding to use Uva in his plan instead by turning him into the Medal Vessel. Leaving Kiyo-chan to Chiyoko's care as he no longer needs the doll to speak normally, Maki proceeds to engage Kamen Rider OOO and Ankh in the final battle. In the end, after being mortally wounded by Kamen Rider OOO Tajadol Combo with a purple Core Medal-powered Giga Scan, Maki's body becomes a black hole-like collapse and sucks in most of the Core Medals along with himself as he delights in his own death.
During the events of Kamen Rider OOO: Nobunaga's Desire, Maki forcefully provides Nobunaga with the three black Core Medals to have him assume his Armored Warrior Inhumanoid's complete form. Then in the events of Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals, Maki gives the Greeed one of his Core Medals to help Eiji in his fight against Gara, stating that though both he and the alchemist embrace destruction, their ideals of what is to occur after it are extreme opposites.
Kiyoto Maki is portrayed by Yuu Kamio (神尾 佑, Kamio Yū?). As a child, Maki is portrayed by Hayato Watanabe (渡辺 隼斗, Watanabe Hayato?).
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