When his grandfather passes away, Daikichi Kawachi, a 30-year-old aimless bachelor, discovers a hidden family secret—a young girl named Rin, his grandfather's illegitimate daughter. Despite the family's rejection of Rin, Daikichi steps up and decides to become her guardian, delving into the uncharted waters of parenthood. Usagi Drop follows Daikichi's heartfelt endeavor in raising Rin, showcasing the tender bond that blossoms between them and the joys of building a loving family.