What exactly happened to Han Tae Sun after he left Oska during his concert?

It has been 5 years since he'd left. Oska is now married to Yoon Seul and of course, Kim Joo Won is with Gil Ra Im and their 3 children.

What about the girly, skinny, tall and pale man? The man who Oska chosen to produce his songs? The man who had Oska in his heart?

The man... who is Han Tae Sun.

As we all know  Oska's real name is Choi Woo Young and his family only consisted of his mother and him. However, what we didn't know was that there was another girl in the family. 

She was Choi Joo-Eun, the sister of Oska, the daughter of Oska's mother and Oska's father and the cousin of Kim Joo Won and Kim Hee-Won, niece of Joo Won's mother and grand-daughter of Oska's, Joo-Won's and Hee-won's grandfather, Grandpa Moon.

Joo-Eun loved her family as much as they loved her but the only thing she hated was that her family were very strict with her and ordered her to study business management from young so that she could help run the business when she grew up. Also, they made her go on blind dates from young. Even though her family done that, she was still the apple of everyone's eye; they dressed her up nicely from young and spoilt her with gifts and presents.

One day, she decided pursue her studies- what she actually loved doing: writing song lyrics, creating the tunes and composing her own songs. Therefore, ignoring her family's strong objections, she left for Japan's School of the Media, Arts and Entertainment.

That was about 7 years ago. Now, she was taking her third degree in performing arts which she already have 2 degrees in. She was still keeping contact with her family members almost all every minute of her life, but she kept it a secret that she was related to them to anyone, in case they judged her on being a spoilt brat. She was nothing like a rich diva but a down-to-earth, humble, clumsy and cute girl. Nevertheless, she had the good-looks from her family in her blood.

However...

When Han Tae Sun, after roaming around, doing odd jobs and still composing songs for Oska and sending them to him by mail every now and then, refusing to see him or anyone else from 5 years ago so that he could forget all about the past, enrolled in that school. It happened to be that Tae Sun also chose to take performing arts as his course and because he was so talented, he went to the third degree class, like Joo-Eun.

What will happen when the both of them meet? Like Tae Sun and Oska who both had clashing personalities, what will happen when Han Tae Sun meets the sister of Oska? Will sparks fly between them? Will Han Tae Sun change his preferences? Or more accurately, will Joo-Eun be able to change him?