Exactly What’s Going On?

A coffee shop owner, Il-woo, and a nail artist, Anna, are in a happy romantic relationship; they keep their relationship a secret because of their age difference. One day, Anna's grandmother gives Anna a magic card; the card is to make her wish come true. She turns into a 10-year-old girl, Hannah; Anna's wish to become young comes true!

A secret romance between a 40-year-old woman and a 25-year-old man gets complicated.

Il-woo believes that something is wrong with him because when he is with Hanna, he feels as if he is with Anna; he finally discovers the truth and the girl leaves his home and goes to her grandmother, who consoles her for what has happened.