Hasebe Shinji's relationship with his father was never that good. On the way home on the subway, he hears about his father having been hospitalised. While getting off though, he catches a glance of who seems to look like his brother -- presumes to be dead for many years now. He follows this man into the exit and finds himself in 1964, where his strange adventure into his own family's past begins.
I must say, this is one of the weirdest films I've ever seen. It starts off quite interesting, but then it becomes a sort of pureé of... ideas, mostly. While the ending, or well, the 'twist', was good (I didn't see it coming), what happened right afterwards must be one of the most ridiculous scenes ever, leaving you with a sore feeling.
In short, nice idea, and while I really like the main actor, bad execution / wrapping up of a story.