You are in an adventure squad that explores various dungeons. One day as you visit a dungeon you see a lone girl crying. Your squad members are skeptic but you immediately rush over to comfort her. She appears to be a demon girl. She seems very lonely, so you decide to invite her to your squad. Months go by, and since she joined your squad no dungeons are a threat anymore. One day however, you come back from your trip to see your squad missing and there she stands... The demon girl Selena...