The story revolves around a 23-year-old man named, Kazama Masamune. During high school, he had a girlfriend four years older than him, but she suddenly decides to go study abroad. Six years later, he receives news that she has passed away. In addition, she secretly gave birth to Masamune's daughter. Now the five-year-old daughter, Koharu, is left without a mother, and Masamune decides to raise her on his own.