Childhood friend and flirty? Man won the lottery and he has the willpower of a saint to resist such temptations. I don't say this often, but: God, I wish that were me.
Kitsunes are the best and I'm glad there's more works with them. He better treat her right.
Not willpower. Stupidity. To not realize a girl chasing after you for most of your life desperate to capture your attention has a specific reason for wanting your attention is just plain dumb. I get it when it's a recent development (Nagatoro, Anjou-san, Yamada, Akutsu, et al), but this ain't that.