Brief Explanation

A boy and a girl fall in love with each other in a party. But the boy finds that the girl is providing some sort of drinks to her friends. So he decided to stay away from her. She wants to know why, and he clearly states that he is not a bad person, so he doesn’t want her to touch the “bad” thing, which he means Yakult. And all the misunderstanding is just because 40 years ago, most people did not know what Yakult was, and they even thought that it was harmful to people.