A loud, brash 12-year-old who is part of a childhood friend group consisting of himself, Saki, Shun, Maria and Mamoru that attends Sage Academy in Kamisu 66. Satoru is a quick-witted and observant person who cares a lot about his friends despite poking fun at them. He is shown to be particularly close with Saki, as he teases and argues with her more often than the others. Like the rest of the students at the academy, he has a psychic ability called Cantus. During summer camp, the group of five go off on a wild adventure that leads to Satoru and Saki being separated from the others and them meeting a Queerat named Squealer, who appears trustworthy at first but seems to have dangerous intentions.

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Satoru and Shun begin a physical relationship when they become fourteen, much to Saki's despair as she had also liked Shun. When Shun mysteriously passes away and the administration of Kamisu 66 erase and replace him with another student named Ryou in everyone's memory, Satoru and Saki are the only ones who are able to vaguely recall him. The two get even closer, both emotionally and physically after Maria and Mamoru run away together.

Spoiler

When he is 26 years of age, Satoru works as a researcher at Lotus Farms. He narrowly survives when the Queerats set their first attack against humanity during that years Summer Festival. Together with Saki and several others he travels to Tokyo in order to defeat the 'Messiah', who is not only a weapon for the Queerats but also Maria and Mamoru's child named Akki, or Fiend.

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After the Queerats are defeated and Squealer's subsequent trial, Satoru discovers an unsettling truth: modern Queerats are descendants of actual humans - specifically those who did not have Cantus - that had naked mole rat DNA forcibly inserted into their genome.

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Satoru and Saki are married a couple years after the Queerat attack. When he is 36 years of age, Satoru is the head of Lotus Farms and he and Saki are expecting their first born, hopeful that society will have changed for the better by the time the child grows up.