Momo is the youngest daughter in Hirai family and due to that, her father favored her so much that he need to make sure that she is behaving just right as their family's company next successor. Much to his dismay, Momo is a wild and free kid, who does everything she wants and desire. Because of that, Hirai Shiro decided to married Momo to his friend's daughter, Myoui Mina. 

     Mina is the only daughter of Myoui Kazama, who grew apart from him since she was a child in overseas. She lost her mother since birth. Kazama agreed of his best friend's proposal because he wanted to see her daughter happy in someone else's care other than him, knowing that he was too old to take care of her 24/7. 

     However, none of them agreed relently to this marriage. The marriage still happened and they lived together in Momo's apartment, because of their parents' demands. Due to their stay, Momo had warned her about that one room at the end of the hallway and Mina doesn't even know why she was banned from entering it. While Momo was being a cold heart creature, Mina believes that Momo is actually hiding something from her. A secret that never have been told. And she too believes, that all answers to her questions are just right behind the secret door.

* * *

"By the way, my name is Hirai Momo, not Mono."

"Tch. I don't care. I still gonna call you whatever I want."

"Should I call you Mini then?"

* * *

One question. One secret. One answer.

Will love grow between two cold hearts?