
I think it's a twin sister, since Akira called her name ("Tsukino's dress") and not "Mom". On the photo where Akira and Tsukino together in front of the clinic they looked like the same age, and both of them with the brother stood at the back in the family photo--the place
usually for kids. My guess is probably that the twins had a striking resemblance to their (late?) mother, which made their father adored Tsukino with the most resemblance to their mother. But she probably died and the role turned to Akira. I just hope Tsukino's death wasn't too dark, but seeing how Minato family background was, idk what to prepare myself into
Am I the only one who is disturb by the way the director's father is looking at his "daughter" ?? damn creepy... I hope their story (director and the glasses guy) is not too shocking......