'Where have you been all this time? I thought you will be my first & last love but unfortunately we can't be together'

Jungkook (1997) & Yein (1998) were two siblings aged just one year difference and they have been separated since childhood. Yein was adopted by a pair of husband and wife who owned a bakery while Jungkook was adopted by a husband and wife who is also known as the richest person in Korea. They went to a same school & also being in the same class cause Yein is smarter than other people at her age. Jungkook was fallen for Yein even he knew that Yein's bestfriend, Mijoo have a feeling for him for a long time.

'How can they being together if they were siblings?'

'They're not even know that they were siblings'