One of the problems with getting older is that you start to recognize patterns across years - in this case, a style of movie-making. This movie falls squarely into the "the love of my life is dead and has returned as a spirit to help me" school of film-making. Its most obvious predecessors are "Ghost" (1990) and "Truly, Madly, Deeply" (also 1990), but I'm sure there are others.
In this case, the movie starts by introducing us to Hinako Mukaimizu (female, student and surfer, age 21), and Minato Hinageshi (male, firefighter, age 19), and their relationship as it blossoms into true love. But he dies saving a life, and we stumble into the cheesy fantasy visitations that are the point of the movie. Both the fantasy aspects of the movie and the more real-world aspects are sloppily structured, the characters are overly broad, the dialogue is mediocre, and the heavy reliance on a poorly sung pop song (it sounds like crap in both English and Japanese, so this appears to have been intentional) is insult-to-injury. On the plus side, it looks pretty - but overall, very disappointing.