Clearly these guys have "affection" because they are all apart of the same "curse" you could say. It's not romantic, it's more that they cherish each other's company.
I was thinking he was more of a son to him, he did say he was a father to him. Also they dont act yaoi they just act like friends, what with their constant chasing of girls.
So, when I first started to watch this, I thought Doza was Kiyoi's brother. Now, I'm pretty convinced he was Kiyoi's gay lover and that, after he died, he choose Ageha as pick of the litter as replacement. Epic. "Papa to Kiss in the Dark."