Intro. You are a child who has fallen into the Underground, an underground place where men have locked up monsters considering them " dangerous, you meet Sans, a skeleton created in the laboratory by monsters, given that every human being has a different soul with a different power, the most powerful is determination but the fallen boy has a white soul of which nothing is known, the red soul is determination, blue patience, orange courage, blue integrity, purple perseverance, green kindness, yellow justice. Monsters are weaker than human souls but have their powers, and are unable to absorb them because they do not sustain the power apart from Sans who succeeds. despite being very fragile and having one HP he is the strongest. The monsters want the souls of the children to break the barrier that confines them. They have 6, one is missing (yours).