Kippei Katakura, a popular high school guy with a reputation for dating many girls, actually harbors deep feelings for a specific girl named Kokoro Tokunaga. His world takes a turn when his family entrusts him with the care of his abandoned 5-year-old cousin, Yuzuru Sakashita. While waiting for Yuzuru's mother to return, Kippei becomes her temporary guardian, forming a strong bond with the young girl. Through this experience, Kippei not only discovers the challenges of childcare but also the value of genuine connections. Juggling his attention between Kokoro and Yuzuru, they embark on a journey of growth, understanding, and redefining the essence of family.