I don't really know him that well.

[ A beat... and this shows Kojis observational abilities here as he idly comments, ] He was always watching us in the past. So I guess he's that sort of guy who pays attention to things.

[ He does not, of course, connect Rin's been into Junko this whole time. He just observes that their Uncle Rin has observed him and Junko then they played together when they were younger. He may have been trying to be covert about it, but still ]