Sumi handed out drugs at a famous party and was generally a pretty chill person. When the party started getting violent however, she stood by laughing at the carnage. With the chaos unfolding she unfortunately was the first to be inhabited by a demon. While it's unclear what her fate ultimately was, given the demon transformation is irreversible and the general treatment of demons by the government it's likely she died some time after this (we don't see her again).
