This is a story about an old 50 year old man, who starts to fall in love with a 20 year old. And the 20 year old almost starts to fall in love with him.
However, I think because it was a Japanese drama they just never really go there, by the end of it, the relationship is still up in there.
It would have been different if they made the 50 year old guy a bad guy, but he's not, and the 20 year old is also not really a bad person getting into an affair with a guy who is married. They just kinda of meet, and it goes nowhere. The title of the drama should be, I met a 20 year old, and felt some butterflies, and nothing happened.