Every Wednesday morning, Sehun found a mineral water in his desk drawer. A sticky note was attached to the bottle with a simple message on it . To : Sehun ‘Human body is mostly filled with water, be healthy’, it was one of the message. He received different message (actually a scientific information) every Wednesday related with health issues. It was always the same mineral water with a same colour of sticky note. He was curious on the person who give it to him. He started to observe his surrounding, ready to seize anyone who had suspicious act every Wednesday.