Book 6

So Takaya actually tried calling Naoe once (after Chiaki blew up at him and before Ujiteru found him).

Naoe was out so his mother answered the call, telling Takaya that Naoe was on some long trip as well as mentioning that her son recently went out out with some woman and didn't return home for a few days.

And Takaya is basically, "WTF, here I am trying to fix our confusing relationship and he's out fooling around with some woman..."

LOL

Except that I suspect that 'woman' was Asaoka - the woman whose brother's soul got eaten by the Tsutsuga beast... not sure though. It was her.

But still a pretty amusing telephone conversation.