Twenty years have passed since Tomoya killed the seven year old Kiyotaka. Tomoya's younger brother, Naoto, is born after the incident. They have a close relationship, but at the age of 24, Tomoya leaves home, and later, when Naoto is in his second year of high school, he finds out about the crime his brother has committed. Feeling betrayed, he ends up hating Tomoya and distancing himself from his mother and all the people around him, thus living in solitude. One day, he meets Kana and is saved by her cheerfulness. When they decide to get married, he tells her he doesn't want to have kids. But Kana ends up getting pregnant.