@DirkHardpeck
The point of the arc I feel was to prove that Kotoka can go without fetishes. She loves him with or without licking his back. But the entire time he complained, whined, begged and tried to sneak in hair touching.
Perhaps I'm weird, but I don't really see this to be true. Actually she proved to be the most desperate and hypocritical one.
In chapter 46 you have Tatsu suggesting to do her hair and she refuses because fetishes are banned. A few pages later we see this
Did we see Tatsu licking her hair from her comb? I do not recall this happening. Maybe it happened off-screen, but this is not something on which we can discuss. Did we see Kotoka sniffing his shirt? Yes, we did. Among the two, she proved to be the one most affected by fetishes according to me.
As a joke, her mother was shown to almost cheat her husband after seeing Tatsu's back. Are we sure that Kotoka won't do it seriously if someone with a nicer back will appear? She constantly tests Tatsu, but I don't see the same effort from her to prove her love.