Ran believed Shinichi was away, but she didn't waver. The only times that changed was when I could be Shinichi for a brief time or when she thought 'Conan' was 'Shinichi.'

Even if I was across the galaxy, across all the dimensions. If I was at the farthest possible point I could be from Ran...that bond won't change. If she can wait twenty years, I could wait just as long. Even if it was just a day before the end of eternity, if I could just be with her properly for even an hour, a minute...

I could wait that long.

Why does a demon envy that? Wouldn't they have all the time in the world?