The father of the Nagisa family had continued to work hard solely for his daughter Mitsuki after the loss of his wife. Seeing her father's dedication, Mitsuki grew up bright and cheerful, yet secretly struggled to suppress her intense romantic feelings toward him. Every day, she resorted to masturbation to ease her longing. However, one day when her father mentioned remarrying, her pent-up emotions erupted uncontrollably. She began demanding unreasonable things she'd never voiced before, spiraling into obsession. Here begins the moment their father-daughter relationship changes forever, as the boundaries between parent and child start to crumble.