Zenzo Kotoura is Kumiko's father and Haruka's doting grandfather.
Zenzo is a somewhat carefree man, who loves his granddaughter, Haruka, and dotes on her. Zenzo is perverted (though not as much as Yoshihisa) and has frequent perverted thoughts about Haruka (particularly, her butt and thighs) and is, thus, initially distrustful of Yoshihisa. However, this doesn't last long, as Zenzo soon warms up to Yoshihisa, actively supporting his and Haruka's relationship, though he does get irritated at Yoshihisa's ineptitude, and letting perfect chances go to waste. Zenzo is apparently estranged from his daughter Kumiko, following her disownment of Haruka. This is supported by episode 9 of the anime, where upon running into Kumiko and her date at a hotel, he mentions having told her that he never wanted to see her again. Zenzo is also good friends with the Head Priest, often seen interacting with the latter, who is also fond of Haruka. Zenzo is also more perceptive than he lets on, having discerned Hiyori having some connection with a "random attack on the streets", while having little information to go by. (Though he afterwards dismisses it, claiming to have forgotten the name of the dojo, blaming his advance age)