As a young girl, Shion's life was turned upside down. She lived with both of her parents on Miltian before the conflict. Her mother was immobile and drifted in and out of comas, so she was cared for in a hospital. Shion's father spent a great deal of time working, so Shion was cared for by a Realian named Febronia.

During the Third Descent operation at the end of the Miltian Conflict, Shion's hometown came under direct attack by Federation forces. During the battle, Shion made her way to the hospital to find her parents. She found far more than any child should see as both of her parents were killed by renegade Realians right before her very eyes. Shion would have perished as well, but her brother Jin rescued her.

Jin took care of Shion until she was old enough to take care of herself. As she was exceptionally bright, this wasn't long. She landed a job at Vector Industries' First R&D Division at the age of 18. Her youth, appearance and cheerful personality earned her many friends in the division while her sharp intellect advanced her quickly through the ranks.

She was promoted to Junior Chief Engineer of the KOS-MOS project under Kevin Winnicot. The two were a terrific match and quickly fell in love. The project progressed quickly until Kevin was killed by KOS-MOS when she was awakened prematurely. Shion was present as her and Kevin's creation killed her lover.

Though traumatized and afraid of thunder storms (Both Kevin and her parents were killed on a stormy night), she continued with the KOS-MOS project. She buried her past as deeply as she could and put her cheerful personality once again. Some of those close to her, like Allen Ridgeley, could see through this, but they continued to offer support.

Just after Planet Ariadne vanished, Shion was aboard the Woglinde when it was attacked by a large group of Gnosis. She was grabbed by one, but KOS-MOS self started and was able to save Shion. The consequent destruction of the Woglinde left Shion and Allen inside an escape pod with Andrew Cherenkov clinging to the outside. The Elisa found them and Shion's trip into history began.

She has since left Vector after suspecting that the U.M.N (supposedly constructed by Vector Industries) were closely tied to the Gnosis terrorism. She has many doubts about the events of the Miltian Conflict and has teamed up with Scientia to uncover the truth.