Oh Sehun is a single father. When his wife died of a sickness in a young age, he did his very best to live and provide for the one and only treasure his wife left him; their daughter Yeojin*.

Old Mr. Oh’s teacher, like any other man, has always been his own experience. He knew the world isn’t full of colours, rainbows and unicorns like his wife told their daughter. That’s why he has always been so protective of his one and only treasure. He adored and worshipped her and would only live to please her. He’d do everything just to keep her from harm and tears...

But what if the same protection he was giving is the exact same thing that would tear them apart. What if his only daughter grew to hate him and to have things worse, his doctor found out he doesn't have much time to live.

Will he be able to gain for his daughter's forgiveness before he dies, or will he leave the world without even seeing his beloved daughter and be hated by his little sunshine until his last moments?

*Yeojin - a korean name that means Treasure