Hidesaburo Ueno was a professor at the University of Tokyo. Every morning his faithful dog Hachiko said (say) goodbye to his master at the front door and every evening the dog went to Shibuya station to welcome his master home. One day professor Ueno didn't return on the usual train. He had a heart atack at work and died.
Friends of the professor took the dog to their house to look after him. On the first day when they arrived home from work they found Hachiko was missing.