Please check out the trailer first ^^ at here :

Storyline : Jinri was Taemin's first love from his childhood.
When they grew up, Taemin still had a big crush on her. Jinri wasn't a friendly girl. Jinri's evil father made her become a cold-heart person. Who always scared of the feeling of being hurt.
She usually fought with anyone who made her mad. Jinri's behavior made everybody stay away from her expect Taemin. Because Taemin knew inside that evil mark she wearing, there was an innocently weak soul that she was trying to hide.
Taemin was the only one who smiled to her, the only one who still stayed by her side even when she shouted at him harshly.
One day Taemin had to leave the town they were living in. He was chosen to be a trainee of SM -- A huge entertainment company. It was a big chance for him to chase his dream- becoming a famous singer.
On the last day, it was also Jinri's birthday, Taemin pretended to hold a party for her. He wanted to confess to her.
But Jiri's attitude was still the same. She yelled at Taemin and threw away everything.
Because of her hard life, because of the past with too  much hurt and lost, Jinri always doubted with anyone who wanted to cared for her. She scared that just like her father, someday they would run away and leave her alone.
On that day Jinri's heart was broken because she recognized that Taemin was the most important person to her.
But at the same time, Taemin's heart was broken because of her rude words, too.

The next day, when they met for the last time, Jinri was still stubborn, she tried to be cold to Taemin like usual.
And then they lost the connection to each other after that day....

3 years later... at present
Now Taemin became a famous singer from the group called SHINee. He had been trying to erase his hurt memories from his first love. He hoped time would heal the scars inside his heart.
But one day, something happened and made those scars deeper....
A new trainee called Sulli attended SM. Her face looked exactly the same like Jinri's.
Taemin tried to approve Sulli to find out the truth but she always insisted that she wasn't Jinri.
Then who's Sulli ? Who's Jinri ?