You live in a dystopian futuristic city called The Capital, in here the crime rates are high due to the Sinners, a Terrorist group. That's why a tactical team was formed by The Cardinal to stop them called Saints. The Cardinal is a government organization that runs The Capital. Kanna is walking home when she suddenly lose consciousness and fall to the floor.

Kanna: while lying on the floor "Ugh.. my head hurts.."