Nono's introduction, especially in the manga. "This is my ocean."
And Nono, again, in the anime's conclusion, when she asks Hakim what's a "country," because she can't see Earth's borders from her Lunar home, which makes him realize how pointless his war is and changes his mind about killing her.
"Please save Yuri." And Yuri sending out a flower into space in the memory of his late wife.