Naoyuki is Tomoya’s father. Tomoya’s mother Atsuko Okazaki died when Tomoya was young, thus leaving only himself to raise Tomoya. After the accident, Naoyuki turns to alcohol and smoking, and held frequent fights with his son. One day while arguing with his son on trivial things, he slammed Tomoya against the wall, dislocating Tomoya’s right shoulder. Immediately after that, Tomoya refused to come out of his room, and by the time he finally went to the hospital, it was declared to be untreatable. Ever since then, his father has treated Tomoya more kindly, but like a stranger rather than family. This only hurt Tomoya even more, so he becomes a delinquent, as he is unable to participate in basketball activities any longer, and he avoided returning to his home early enough to be confronted with his father. Tomoya has the intention of running away from his home, as revealed from Kotomi’s path.
As revealed from Shino’s story about Naoyuki, even though his wife has died and has become depressed, Naoyuki sacrificed everything in his life just for Tomoya’s sake, hoping Tomoya to grow up to be a proper man unlike him. After Tomoya comes to term with his father, Naoyuki decides to return to his hometown to stay with his mother, claiming his role as a father has finally come to an end.
In the movie, Naoyuki works a graveyard shift instead of staying home and becoming a drunk. He also cares about his relationship with Tomoya and even tries to ease his son’s depression in order prevent his son from becoming like him.