Satoru was childhood friends with Saki, Maria, Shun, Reiko, and Ryou. He was among the last, along with Saki, to graduate from Harmony School. Upon entering Sage Academy, he was assigned to Group 1.
Prior to the summer camp, Satoru's horror stories had inspired the group to pick the creatures in the rumors as their camp topic (this occurred during the camp in the anime). During the camp, the group ventured to the far shore of Lake Kasumi and captured a False Minoshiro and learned the truth about humanity's bloody history. However, before they finished questioning the False Minoshiro, they were caught by the priest Rijin, who sealed all of their Canti. On their way to the Temple of Purity, they were attacked by the Ground Spider colony. Rijin was killed, and Satoru and Saki were captured by the Ground Spiders.
Using the fake haythatcher egg that Satoru pocketed earlier during the canoe ride, they were able to escape and ran into the Robber Fly colony, an indigenous Queerat colony defending against the Ground Spider invaders. The Robber Fly envoy, Squealer entreated them repeatedly to aid them against the invaders. Satoru and Saki were brought to greet the Robber Fly queen and allowed to retire for the night. During the night, a sneak attack by poison gas trapped the duo underground, wherein Saki thought of a way to restore Satoru's Cantus. Though they were able to escape, Satoru insisted on attacking the Ground Spider colony, with Saki acting as his extra pair of eyes, and Squealer guiding them. During this, Satoru's concentration was stretched thin, rendering him unable to continuously use Cantus. Just as they appeared to be cornered, reinforcements from the Giant Hornet colony arrived, led by Kiroumaru. Satoru saved Kiroumaru from a Balloon Dog explosion with his Cantus, knocking him unconscious.
When Satoru awoke, he and Saki attempted to escape the Queerat camp and return to Lake Kasumi. However, they were discovered by Squealer. Satoru and Saki persuaded Squealer to lead them to Lake Kasumi, where they met up with the rest of the group and safely returned to the town.
After the first timeskip, Satoru and Shun became lovers. The latter later ended the relationship abruptly. Seeing no chance to get back together, Satoru approached another boy from Group 5, Rei, who had shown interest in him for a while.[1] However, when Shun later went missing, Satoru insisted that they had to search for him.
After Shun's death, Satoru's memories of him were replaced with Ryou, though he and Saki later concluded that Ryou was not the person they both loved. They then formed a duty pair at Sage Academy and persuaded Maria and Mamoru to investigate their friends' disappearance.
When Mamoru ran away from the villages, Satoru searched for him along with Saki and Maria. Satoru left Mamoru in their care while he returned to the town and was questioned by the Board of Education. Later, due to Tomiko Asahina's intervention, he was allowed to search for Maria and Mamoru again with Saki. During this time, he acted as Saki's support, though they were in the end unable to find their friends. Through Squonk, Satoru learned of Maria's wish to leave the villages with Mamoru and her request to tell the villages that they had died.
After the second timeskip, Satoru had graduated from Sage Academy and had begun work at Lotus Farms. Due to a skirmish involving the Spider Wasp colony that worked for the farms, he was sent to the Department of Exospecies Control to investigate further. As events with the Queerats progressed, Satoru discovered at a Security Council meeting that Maria and Mamoru had died, and their bones had been returned to the village two or three years after their disappearance.
At the Summer Festival, Satoru was spared from the initial Queerat attack due to chasing after Saki, away from the main square. During the first wave of attacks, he realized that the Queerats were using poison gas and warned the village leaders, allowing them to block the spread of the gas in time. He and Saki later joined three other villagers from the metallurgy plant to patrol for Queerats, and went to the hospital where they witnessed the Fiend's attack. He and Saki were the only ones to escape the hospital.
While traveling back to into town to warn the other villagers, Satoru was separated from Saki, but managed to reunite with her in time to witness Shisei Kaburagi defeated by the Messiah. The two of them escaped to the Temple of Purity and learned about the existence of the Psychobuster from the Mizuho Watanabe's letter. Together with Inui, Kiroumaru, and the fake False Minoshiro, they went to Tokyo to retrieve the Psychobuster.
In Tokyo, they split into two groups: one to bring the submarine and the other to lead Yakomaru's soldiers on a wild goose chase. Satoru was with Kiroumaru in the latter group and was injured in the process. Despite his injury, he insisted on carrying the Psychobuster when Saki successfully retrieved it and rendezvoused with them. Following Kiroumaru's suggestion, they laid a trap for Yakomaru and the Messiah; however, it failed and as the Messiah approached, Satoru threw the Psychobuster knowing that he would be infected as well. In order to save Satoru, Saki burned the Psychobuster and Kiroumaru returned to help them make a brief escape from the Messiah.
It was during this reprieve that Saki realized the true nature of the "Fiend" and using Kiroumaru as a sacrifice, the Messiah was defeated. Satoru and Saki captured Yakomaru and brought him back to the villages for trial. During the trial, Yakomaru, now Squealer once more, shouted that the Queerats were human to derision. However, this prompted Satoru to look into Queerat DNA and discover that they were indeed mutated humans with naked mole rat DNA inserted into their genome, so as to not trigger death feedback. He reluctantly shared this discovery with Saki.
Two years later, he and Saki married. At the end of the series, ten years past the Queerat attack, he became the head of Lotus Farms and even though he was supervising the breeding of Tainted Cats, he believed that by the time his and Saki's child grew up, their society would have changed for the better.[2]


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