Real quick

I can’t really remember the manga but this reminds me of this other manga with a similar plot. So this young man went to visit his grandmother and at night this man came mistaking him for his lover and when he woke up he asked his grandmother about it turned out the man had died in a war away from home and his lover who was waiting for him also died later on of old age. So the young man who visited him that night was a ghost who finally made it back home to his lover only to find out he is dead.