The story of this anime revolves around a group of children (now teenagers) that have grown apart over the years and for some reason one of these teenagers starts too see the ghost of an old friend.
The story is quite sad, so if you don't want to get sentimental, then this anime is not something for you.
Have you already watched it yet? How do you rate it?
Not quite sure if we are allowed to post links to streams for it so I'll just say use google if you're interested and stick to Japanese dubs with English / your language subs for a good experience!