Ever wondered if your siblings are really yours? Have you ever thought that there might be a secret as to your relationship as siblings? 

Kwon Yuri is the 18 years old noona and Jeon Jungkook? Her 17 years old dongsaeng.They were the 'step siblings' that never knew the secret of their relationship.

When Yuri was 12,her family got into an accident and only her mom and her survived the ordeal while her father and younger brother passed away unfortunately.

For Jungkook,he was an only child which made him really lonely at home until Yuri was introduced.Well,in his case,his parents sought a divorce when he was 14 and that was when he last saw his mom and has been staying with his dad since then.

And somehow due to their work relations,her mom and his dad met and finally got married to each other.

And that was how Jungkook and Yuri was introduced as each other's 'step sibling',in which they though was real.

But another thing about the two,they never got along well.Bickering has become a hobby for the two.The two found it fun but the one usually who starts throwing spiteful remarks is the older one,Kwon Yuri.Well,partly because the younger one,Jeon Jungkook,is always irritating his noona.

But there's something in Yuri that makes Jungkook very very interested in her in which teasing might help,he wish.

But the older one doesn't feel anything about her younger brother,well other than the fact that they're siblings. Or, does she?

But there was a secret.ONE.