Usually seen smiling, Maria is one of the central characters of the series. Two years ago during the events of 428: Fūsa Sareta Shibuya de, she was mistakenly abducted by Snake terrorists who mistook her for her twin sister, Hitomi Ōsawa, their true target as Hitomi's blood was resistance against the Ua virus. Snake later infected Maria with the Ua virus to force her father, Kenji Ōsawa, to make them a cure to the Ua virus to save her life. While her life was saved thanks to her father's anti-virus, the trauma she endured during the Shinjuku incident made her suffer Amnesia. As a result, she can't remember certain events during that incident; including not remembering having meet Alphard before. Prior to the Shinjuku incident, she befriended Canaan after being saved from hoodlums during a trip somewhere in the Middle East. As her dream is to become a photographer, she became the partner of Minoru Minorikawa before the pair's assignment in Shanghai and her subsequent reuniting with Canaan.