KOS-MOS is an anti-Gnosis battle android, designed to combat the menacing enemy called Gnosis. She is equipped with the Hilbert Effect to make battle with the mysterious force possible in our dimensional plane. Her two main objectives are to eradicate the Gnosis, and to protect Shion. But being a machine, the means by which she achieves her goals are through logic and probability which can make her difficult to deal with at times.