I went back and watched it and I got what you mean.Somehow I missed the fact that the black blob below was the back of Kiku's head. What do you think Yao is doing standing behind Kiku? Tying his own hair?

Though i think maybe the first frame is Kiku staring across the sea (towards Yao's direction?) and thinking about the past and then the rest of it are all memory sequences...

Anyway it's creepy :X I sort of have a phobia of mirrors in case I see something that's not supposed to be there behind me.