Substitutes don't stay that way forever. Eventually they grow and evolve into their own place in the person's heart. Not to be better than the lost, simply different. Take it from someone who knows. After a loss we are all a bit empty but, because the world keeps turning, we must heal and keep moving forward -- there is no other direction to go.
its really touches my heart...
to be honest i don't like sad ending. so thats why i always avoid tragedy mangas.
i dont think kanata will remain a shell for long cause he loved hisakuni from the start its just that he spent so much time with yuki (person with the same face as hisakuni) that he thinks that he is in love with him. And all that stuff about also giving the other also to yuki would probably be because he feels guilty cause yuki died. I think that hisakuni and kanata are meant to be together if that STUPID accident hadnt taken place then i think kanata wouldnt have even looked at yuki as anything more than a friend.
I pity Hisakuni. He has to live with that 'empty shell', cant get enough love after all of this time, and being substitute for his brother.
Poor you, boy, poor you...