|Novel Debut||Volume 4|
|Manga Debut||Volume 7 Chapter 35|
Their only interaction was shown to be their phone call after the events of the "King Game" but it gave a few hints of what their relationship might be like. Hayato seems to trust Kodaka as he let him live alone, and look after his sister (though he himself acknowledges his lack of parental care). He also seems to like teasing his son. Before Kodaka's birth, Hayato began working hard to afford buying a home that could satisfy his wife's tastes, and seemed to understand what kind of responsibility he must take in order to raise children.
Hayato, in contrast to Kodaka, dotes his daughter and listens to her wishes (because he feels guilty for long absences due to work), buying dvd and merchandise related to "Kurogane no Necromancer" no questions asked. He calls her "my little angel" and gets very angry if he suspects that some boy may be going out with her.
He and Tenma were best friends since school times. It was Hayato who introduced Tenma to alcohol. Such instances are no rarity in their relationship as in contrast to Tenma, Hayato has been a straight-forward and outspoken person. Since then they've been drinking together. They both seem to regard times of their friendship as precious and reminisce about it quite often.
Hayato cared and loved his wife very much and was in distraught - knowing his wife had died in an accident. Due to this, he dedicated his life in raising his only two children to the point that where he had to go overseas for his job.