Bea is an angel. She died because of brain cancer. She's a cheerful girl, she loves helping people in need and she still wanted to continue life on earth. So God called her to be an angel to help people secretly on earth. 

One day, God called her for a special mission. 

"I want you to make Kim Sunggyu smile." says God. Bea cringed at the mention of his name, Kim Sunggyu. Bea had a boyfriend and it's Kim Sunggyu. She loved him so much that she never told Sunggyu about her disease because she knew that it would make him worry about her and she didn't want that to happen.

"K-Kim Sunggyu? M-My boyfriend?" she stuttered. God nodded and said, "He never smiled ever since you left. Now, I want you to make him smile. Let him feel that you're there with him." "But that would just make him cry and mourn over me again. I don't think I can do this." says Bea. "Yes, you can. I will give you ten days to fulfill your mission. If you have fulfilled it, I will give you a big reward. Remember, only Sunggyu can see you and nobody else." says God. Bea smiled and said, "Yes, I will fulfill your mission." then she left for her mission. 

~on earth~

"Hmm.. Where could he be?" Bea thought. She didn't know where he was so she tried going to their house. Luckily, Sunggyu was there in their room. "Sunggyu-ah~" Bea sang. Sunggyu slowly looked up and cried. "B-Bea?" he cried. Then Bea sang, 

"Cause if one day you wake up and find that you're missing me, and your heart starts to wonder where on this earth I could be" - The Script - Man Who Can't Be Moved

"Bea please, don't" Sunggyu cried. Bea opened the door and found Sunggyu staring at her. "S-Sunggyu, it's me, Bea." says Bea. Sunggyu ran up to her and hugged her tightly like he never wants to let her go ever again. "I miss you so much." says Sunggyu while hugging her. "I miss you too, boo. How are you? Did you take care of yourself?" Bea asked. Sunggyu kissed her and replied, "Yes I have, so don't worry about me, okay?" Bea smiled and said, "Sunggyu-ah, since I'm here, can you do me a favor?" Bea asked the male. Sunggyu stared at her with love and replied, "What is it, babe?" Bea smiled and said, "Smile for me please?" Sunggyu immediately smiled and kissed her again.