Jaein, an ordinary high school student, faces a series of tragedies: his father's death, his mother's demise from a rare disease, and his own terminal illness. His blind younger sister is also being used by a relative to extort insurance money. Overwhelmed, Jaein encounters a shadowy figure named 'D' in a dream, who offers to extend his life by seven days for every person he kills. After accepting, Jaein gains the ability to read people's intentions and becomes a 'Holder', a person who imprisons monsters within themselves.
