*might contain spoilers*
Shinichi's best friend and love interest. She is a thoughtful, tender-hearted young girl who cares deeply for her friends. While Satomi and Shinichi study at the same school and see each other everyday, their relationship is strained to the breaking point when Shinichi’s life is thrown in turmoil by the Parasites. From the moment she is introduced, Satomi is depicted as being attracted towards Shinichi due to his kind and sensitive nature. Consequently, she is utterly grief-stricken as she watches him grow ever more cold and withdrawn over the course of the story.
Despite her best efforts to find out the reason behind Shinichi’s behavior, Satomi becomes increasingly estranged from him as he desperately strives to keep her in the dark about Migi and the Parasite threat. As a result, she begins to question whether any trace of the gentle, caring boy she originally fell in love with remains. After losing nearly all hope, Satomi’s faith in Shinichi is completely restored upon witnessing him crying freely while protectively cradling Reiko’s orphaned baby in his arms. Upon learning that Shinichi is part Parasite at the end of the series, Satomi firmly proclaims this does nothing to diminish his humanity because he still regards all life as precious.