Permanent Substitute [SHINHWA]

Kahel never anticipated her older brother's untimely death. He betrayed his sister for not letting her know about his terminal condition. She was so devastated to the point that she can no longer think of pronouncing the word "Oppa" again to address someone.

Her older brother was naturally loving and playful. He already predicted her probable reaction upon his sudden absence in her life. He left Kahel with a gift inside a Pandora's box to somehow serve as his last remembrance.

The keys were handled by six permanent substitutes who were living at his older brother's dorm and will eventually become her dorm mates as she tries to unlock the chest.

"Each of them has a riddle for you to answer. They will ask you when they think that you are ready but keep it in mind that it will only happen once. A key will be given to you in every correct answer together with an extra item too. Exciting isn't it?"

P.S. The box has 6 locks sooo you won't be able to open it if you miss one key XD