Naoyuki Okazaki

Naoyuki Okazaki is Tomoya's father. Tomoya's mother, Atsuko Okazaki, died when Tomoya was young, thus leaving only Naoyuki to raise Tomoya. After the accident, Naoyuki stopped working and turned 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.

Clannad
Tomoya is shown to be on very bad terms with his father, who treats him like a stranger. He goes home late, only to find his father passed out and drunk. Tomoya doesn't like Naoyuki watching or touching him, resorting to violent or aggressive behaviors if he feels that his father is too close to him.

After his homeroom teacher comes to consult his father about his future, being unable to cope with the situation any longer, he decides to move out of his house and starts living with Nagisa. Naoyuki never goes to search for him.

~After Story~
In the After Story, Naoyuki is put in prison due to some problems with his work. This prevents Tomoya from ascending in his job, and he visits his father in prison, taking his anger out on him. He visits him again later to tell him that he is going to marry Nagisa, to which his father consents.

Naoyuki isn't seen until five years later. When Tomoya meets Shino Okazaki, she tells him about all the sacrifices Naoyuki had to make in order to raise him. After Atsuko's death, he promised to try his best for his son, spending all his money on toys and things that would please him. However, due to the long hours he worked and the accumulation of problems he fell into a depression. It was after this that he started having problems with Tomoya. However, after hearing this, Tomoya remembers that Naoyuki was indeed a good parent, being in his same situation now, as he is behaving badly with Ushio. Tomoya feels like he can finally understand what his father was going through and decides to forgive him, admitting that he indeed was a good parent.

After Tomoya comes to terms 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.

Even after Tomoya uses the light orbs to save Nagisa and Ushio, Naoyuki is never seen, but Tomoya tells that he went back to his hometown. Also, it can obviously be assumed that Tomoya would still reconcile with father and introduce him to his family.

Movie
In the movie, Naoyuki plays a vital role. Realizing how depressed his son is after Nagisa's death, he visits the Furukawas and begs for them to help his son.